Enable and add underline button to the toolbar for Markdown formatting (#28169).

Patch by Marius BALTEANU.

git-svn-id: http://svn.redmine.org/redmine/trunk@17385 e93f8b46-1217-0410-a6f0-8f06a7374b81

96 files changed, 154 insertions, 3 deletions

diff --git a/lib/redmine/wiki_formatting/markdown/formatter.rb b/lib/redmine/wiki_formatting/markdown/formatter.rb
index c7611d977..b5ee2c941 100644
--- a/lib/redmine/wiki_formatting/markdown/formatter.rb
+++ b/lib/redmine/wiki_formatting/markdown/formatter.rb
@@ -141,7 +141,8 @@ module Redmine
             :superscript => true,
             :no_intra_emphasis => true,
             :footnotes => true,
-            :lax_spacing => true
+            :lax_spacing => true,
+            :underline => true
           )
         end
       end
diff --git a/lib/redmine/wiki_formatting/markdown/html_parser.rb b/lib/redmine/wiki_formatting/markdown/html_parser.rb
index cee3a2f07..f34034093 100644
--- a/lib/redmine/wiki_formatting/markdown/html_parser.rb
+++ b/lib/redmine/wiki_formatting/markdown/html_parser.rb
@@ -23,8 +23,9 @@ module Redmine
         self.tags = tags.merge(
           'b' => {:pre => '**', :post => '**'},
           'strong' => {:pre => '**', :post => '**'},
-          'i' => {:pre => '_', :post => '_'},
-          'em' => {:pre => '_', :post => '_'},
+          'i' => {:pre => '*', :post => '*'},
+          'em' => {:pre => '*', :post => '*'},
+          'u' => {:pre => '_', :post => '_'},
           'strike' => {:pre => '~~', :post => '~~'},
           'h1' => {:pre => "\n\n# ", :post => "\n\n"},
           'h2' => {:pre => "\n\n## ", :post => "\n\n"},
diff --git a/public/help/ar/wiki_syntax_detailed_markdown.html b/public/help/ar/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/ar/wiki_syntax_detailed_markdown.html
+++ b/public/help/ar/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/ar/wiki_syntax_markdown.html b/public/help/ar/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/ar/wiki_syntax_markdown.html
+++ b/public/help/ar/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/az/wiki_syntax_detailed_markdown.html b/public/help/az/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/az/wiki_syntax_detailed_markdown.html
+++ b/public/help/az/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/az/wiki_syntax_markdown.html b/public/help/az/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/az/wiki_syntax_markdown.html
+++ b/public/help/az/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/bg/wiki_syntax_detailed_markdown.html b/public/help/bg/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/bg/wiki_syntax_detailed_markdown.html
+++ b/public/help/bg/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/bg/wiki_syntax_markdown.html b/public/help/bg/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/bg/wiki_syntax_markdown.html
+++ b/public/help/bg/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/bs/wiki_syntax_detailed_markdown.html b/public/help/bs/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/bs/wiki_syntax_detailed_markdown.html
+++ b/public/help/bs/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/bs/wiki_syntax_markdown.html b/public/help/bs/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/bs/wiki_syntax_markdown.html
+++ b/public/help/bs/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/ca/wiki_syntax_detailed_markdown.html b/public/help/ca/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/ca/wiki_syntax_detailed_markdown.html
+++ b/public/help/ca/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/ca/wiki_syntax_markdown.html b/public/help/ca/wiki_syntax_markdown.html
index 28625f1d4..e6be1fee9 100644
--- a/public/help/ca/wiki_syntax_markdown.html
+++ b/public/help/ca/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Negreta" /></th><td style="width:50%;">**Negreta**</td><td style="width:50%;"><strong>Negreta</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Cursiva" /></th><td>*Cursiva*</td><td><em>Cursiva</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Eliminat" /></th><td>~~Eliminat~~</td><td><del>Eliminat</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Codi en línia" /></th><td>`Codi en línia`</td><td><code>Codi en línia</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Linies de codi" /></th><td>```<br />&nbsp;linies<br />&nbsp;de codi<br />```</td><td>
diff --git a/public/help/cs/wiki_syntax_markdown.html b/public/help/cs/wiki_syntax_markdown.html
index c2b23201f..73bc7b2bc 100644
--- a/public/help/cs/wiki_syntax_markdown.html
+++ b/public/help/cs/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Styly písma</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Tučně**</td><td style="width:50%;"><strong>Tučně</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Kurzívou*</td><td><em>Kurzívou</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Smazaný~~</td><td><del>Smazaný</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Vnořený kód`</td><td><code>Vnořený kód</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;řádky<br />&nbsp;kódu<br />```</td><td>
diff --git a/public/help/da/wiki_syntax_detailed_markdown.html b/public/help/da/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/da/wiki_syntax_detailed_markdown.html
+++ b/public/help/da/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/da/wiki_syntax_markdown.html b/public/help/da/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/da/wiki_syntax_markdown.html
+++ b/public/help/da/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/de/wiki_syntax_detailed_markdown.html b/public/help/de/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/de/wiki_syntax_detailed_markdown.html
+++ b/public/help/de/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/de/wiki_syntax_markdown.html b/public/help/de/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/de/wiki_syntax_markdown.html
+++ b/public/help/de/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/el/wiki_syntax_detailed_markdown.html b/public/help/el/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/el/wiki_syntax_detailed_markdown.html
+++ b/public/help/el/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/el/wiki_syntax_markdown.html b/public/help/el/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/el/wiki_syntax_markdown.html
+++ b/public/help/el/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/en-gb/wiki_syntax_detailed_markdown.html b/public/help/en-gb/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/en-gb/wiki_syntax_detailed_markdown.html
+++ b/public/help/en-gb/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/en-gb/wiki_syntax_markdown.html b/public/help/en-gb/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/en-gb/wiki_syntax_markdown.html
+++ b/public/help/en-gb/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/en/wiki_syntax_detailed_markdown.html b/public/help/en/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/en/wiki_syntax_detailed_markdown.html
+++ b/public/help/en/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/en/wiki_syntax_markdown.html b/public/help/en/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/en/wiki_syntax_markdown.html
+++ b/public/help/en/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/es-pa/wiki_syntax_detailed_markdown.html b/public/help/es-pa/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/es-pa/wiki_syntax_detailed_markdown.html
+++ b/public/help/es-pa/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/es-pa/wiki_syntax_markdown.html b/public/help/es-pa/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/es-pa/wiki_syntax_markdown.html
+++ b/public/help/es-pa/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/es/wiki_syntax_detailed_markdown.html b/public/help/es/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/es/wiki_syntax_detailed_markdown.html
+++ b/public/help/es/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/es/wiki_syntax_markdown.html b/public/help/es/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/es/wiki_syntax_markdown.html
+++ b/public/help/es/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/et/wiki_syntax_detailed_markdown.html b/public/help/et/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/et/wiki_syntax_detailed_markdown.html
+++ b/public/help/et/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/et/wiki_syntax_markdown.html b/public/help/et/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/et/wiki_syntax_markdown.html
+++ b/public/help/et/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/eu/wiki_syntax_detailed_markdown.html b/public/help/eu/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/eu/wiki_syntax_detailed_markdown.html
+++ b/public/help/eu/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/eu/wiki_syntax_markdown.html b/public/help/eu/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/eu/wiki_syntax_markdown.html
+++ b/public/help/eu/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/fa/wiki_syntax_detailed_markdown.html b/public/help/fa/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/fa/wiki_syntax_detailed_markdown.html
+++ b/public/help/fa/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/fa/wiki_syntax_markdown.html b/public/help/fa/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/fa/wiki_syntax_markdown.html
+++ b/public/help/fa/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/fi/wiki_syntax_detailed_markdown.html b/public/help/fi/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/fi/wiki_syntax_detailed_markdown.html
+++ b/public/help/fi/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/fi/wiki_syntax_markdown.html b/public/help/fi/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/fi/wiki_syntax_markdown.html
+++ b/public/help/fi/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/fr/wiki_syntax_detailed_markdown.html b/public/help/fr/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/fr/wiki_syntax_detailed_markdown.html
+++ b/public/help/fr/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/fr/wiki_syntax_markdown.html b/public/help/fr/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/fr/wiki_syntax_markdown.html
+++ b/public/help/fr/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/gl/wiki_syntax_detailed_markdown.html b/public/help/gl/wiki_syntax_detailed_markdown.html
index f5165de5b..2feb48ee5 100644
--- a/public/help/gl/wiki_syntax_detailed_markdown.html
+++ b/public/help/gl/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
diff --git a/public/help/gl/wiki_syntax_detailed_textile.html b/public/help/gl/wiki_syntax_detailed_textile.html
index c28873d6f..ca86fc1da 100644
--- a/public/help/gl/wiki_syntax_detailed_textile.html
+++ b/public/help/gl/wiki_syntax_detailed_textile.html
@@ -185,6 +185,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><ins>underline</ins></li>
             <li><del>strike-through</del></li>
         </ul>
diff --git a/public/help/gl/wiki_syntax_markdown.html b/public/help/gl/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/gl/wiki_syntax_markdown.html
+++ b/public/help/gl/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/he/wiki_syntax_detailed_markdown.html b/public/help/he/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/he/wiki_syntax_detailed_markdown.html
+++ b/public/help/he/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/he/wiki_syntax_markdown.html b/public/help/he/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/he/wiki_syntax_markdown.html
+++ b/public/help/he/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/hr/wiki_syntax_detailed_markdown.html b/public/help/hr/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/hr/wiki_syntax_detailed_markdown.html
+++ b/public/help/hr/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/hr/wiki_syntax_markdown.html b/public/help/hr/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/hr/wiki_syntax_markdown.html
+++ b/public/help/hr/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/hu/wiki_syntax_detailed_markdown.html b/public/help/hu/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/hu/wiki_syntax_detailed_markdown.html
+++ b/public/help/hu/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/hu/wiki_syntax_markdown.html b/public/help/hu/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/hu/wiki_syntax_markdown.html
+++ b/public/help/hu/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/id/wiki_syntax_detailed_markdown.html b/public/help/id/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/id/wiki_syntax_detailed_markdown.html
+++ b/public/help/id/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/id/wiki_syntax_markdown.html b/public/help/id/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/id/wiki_syntax_markdown.html
+++ b/public/help/id/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/it/wiki_syntax_detailed_markdown.html b/public/help/it/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/it/wiki_syntax_detailed_markdown.html
+++ b/public/help/it/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/it/wiki_syntax_markdown.html b/public/help/it/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/it/wiki_syntax_markdown.html
+++ b/public/help/it/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/ko/wiki_syntax_detailed_markdown.html b/public/help/ko/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/ko/wiki_syntax_detailed_markdown.html
+++ b/public/help/ko/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/ko/wiki_syntax_markdown.html b/public/help/ko/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/ko/wiki_syntax_markdown.html
+++ b/public/help/ko/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/lt/wiki_syntax_detailed_markdown.html b/public/help/lt/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/lt/wiki_syntax_detailed_markdown.html
+++ b/public/help/lt/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/lt/wiki_syntax_markdown.html b/public/help/lt/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/lt/wiki_syntax_markdown.html
+++ b/public/help/lt/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/lv/wiki_syntax_detailed_markdown.html b/public/help/lv/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/lv/wiki_syntax_detailed_markdown.html
+++ b/public/help/lv/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/lv/wiki_syntax_markdown.html b/public/help/lv/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/lv/wiki_syntax_markdown.html
+++ b/public/help/lv/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/mk/wiki_syntax_detailed_markdown.html b/public/help/mk/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/mk/wiki_syntax_detailed_markdown.html
+++ b/public/help/mk/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/mk/wiki_syntax_markdown.html b/public/help/mk/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/mk/wiki_syntax_markdown.html
+++ b/public/help/mk/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/mn/wiki_syntax_detailed_markdown.html b/public/help/mn/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/mn/wiki_syntax_detailed_markdown.html
+++ b/public/help/mn/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/mn/wiki_syntax_markdown.html b/public/help/mn/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/mn/wiki_syntax_markdown.html
+++ b/public/help/mn/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/nl/wiki_syntax_detailed_markdown.html b/public/help/nl/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/nl/wiki_syntax_detailed_markdown.html
+++ b/public/help/nl/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/nl/wiki_syntax_markdown.html b/public/help/nl/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/nl/wiki_syntax_markdown.html
+++ b/public/help/nl/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/no/wiki_syntax_detailed_markdown.html b/public/help/no/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/no/wiki_syntax_detailed_markdown.html
+++ b/public/help/no/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/no/wiki_syntax_markdown.html b/public/help/no/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/no/wiki_syntax_markdown.html
+++ b/public/help/no/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/pl/wiki_syntax_detailed_markdown.html b/public/help/pl/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/pl/wiki_syntax_detailed_markdown.html
+++ b/public/help/pl/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/pl/wiki_syntax_markdown.html b/public/help/pl/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/pl/wiki_syntax_markdown.html
+++ b/public/help/pl/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/pt-br/wiki_syntax_detailed_markdown.html b/public/help/pt-br/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/pt-br/wiki_syntax_detailed_markdown.html
+++ b/public/help/pt-br/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/pt-br/wiki_syntax_markdown.html b/public/help/pt-br/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/pt-br/wiki_syntax_markdown.html
+++ b/public/help/pt-br/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/pt/wiki_syntax_detailed_markdown.html b/public/help/pt/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/pt/wiki_syntax_detailed_markdown.html
+++ b/public/help/pt/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/pt/wiki_syntax_markdown.html b/public/help/pt/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/pt/wiki_syntax_markdown.html
+++ b/public/help/pt/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/ro/wiki_syntax_detailed_markdown.html b/public/help/ro/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/ro/wiki_syntax_detailed_markdown.html
+++ b/public/help/ro/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/ro/wiki_syntax_markdown.html b/public/help/ro/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/ro/wiki_syntax_markdown.html
+++ b/public/help/ro/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/ru/wiki_syntax_detailed_markdown.html b/public/help/ru/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/ru/wiki_syntax_detailed_markdown.html
+++ b/public/help/ru/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/ru/wiki_syntax_markdown.html b/public/help/ru/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/ru/wiki_syntax_markdown.html
+++ b/public/help/ru/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/sk/wiki_syntax_detailed_markdown.html b/public/help/sk/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/sk/wiki_syntax_detailed_markdown.html
+++ b/public/help/sk/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/sk/wiki_syntax_markdown.html b/public/help/sk/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/sk/wiki_syntax_markdown.html
+++ b/public/help/sk/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/sl/wiki_syntax_detailed_markdown.html b/public/help/sl/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/sl/wiki_syntax_detailed_markdown.html
+++ b/public/help/sl/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/sl/wiki_syntax_markdown.html b/public/help/sl/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/sl/wiki_syntax_markdown.html
+++ b/public/help/sl/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/sq/wiki_syntax_detailed_markdown.html b/public/help/sq/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/sq/wiki_syntax_detailed_markdown.html
+++ b/public/help/sq/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/sq/wiki_syntax_markdown.html b/public/help/sq/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/sq/wiki_syntax_markdown.html
+++ b/public/help/sq/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/sr-yu/wiki_syntax_detailed_markdown.html b/public/help/sr-yu/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/sr-yu/wiki_syntax_detailed_markdown.html
+++ b/public/help/sr-yu/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/sr-yu/wiki_syntax_markdown.html b/public/help/sr-yu/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/sr-yu/wiki_syntax_markdown.html
+++ b/public/help/sr-yu/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/sr/wiki_syntax_detailed_markdown.html b/public/help/sr/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/sr/wiki_syntax_detailed_markdown.html
+++ b/public/help/sr/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/sr/wiki_syntax_markdown.html b/public/help/sr/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/sr/wiki_syntax_markdown.html
+++ b/public/help/sr/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/sv/wiki_syntax_detailed_markdown.html b/public/help/sv/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/sv/wiki_syntax_detailed_markdown.html
+++ b/public/help/sv/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/sv/wiki_syntax_markdown.html b/public/help/sv/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/sv/wiki_syntax_markdown.html
+++ b/public/help/sv/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/th/wiki_syntax_detailed_markdown.html b/public/help/th/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/th/wiki_syntax_detailed_markdown.html
+++ b/public/help/th/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/th/wiki_syntax_markdown.html b/public/help/th/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/th/wiki_syntax_markdown.html
+++ b/public/help/th/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/tr/wiki_syntax_detailed_markdown.html b/public/help/tr/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/tr/wiki_syntax_detailed_markdown.html
+++ b/public/help/tr/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/tr/wiki_syntax_markdown.html b/public/help/tr/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/tr/wiki_syntax_markdown.html
+++ b/public/help/tr/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/vi/wiki_syntax_detailed_markdown.html b/public/help/vi/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/vi/wiki_syntax_detailed_markdown.html
+++ b/public/help/vi/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/vi/wiki_syntax_markdown.html b/public/help/vi/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/vi/wiki_syntax_markdown.html
+++ b/public/help/vi/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/help/zh/wiki_syntax_detailed_markdown.html b/public/help/zh/wiki_syntax_detailed_markdown.html
index f5165de5b..7696fe6d9 100644
--- a/public/help/zh/wiki_syntax_detailed_markdown.html
+++ b/public/help/zh/wiki_syntax_detailed_markdown.html
@@ -184,6 +184,7 @@ http://www.redmine.org, someone@foo.bar
 * **bold**
 * *Italic*
 * ***bold italic***
+* _underline_
 * ~~strike-through~~
 </pre>
 
@@ -193,6 +194,7 @@ http://www.redmine.org, someone@foo.bar
             <li><strong>bold</strong></li>
             <li><em>italic</em></li>
             <li><em><strong>bold italic</strong></em></li>
+            <li><u>underline</u></li>
             <li><del>strike-through</del></li>
         </ul>
 
diff --git a/public/help/zh/wiki_syntax_markdown.html b/public/help/zh/wiki_syntax_markdown.html
index 27cecc981..4654ddb17 100644
--- a/public/help/zh/wiki_syntax_markdown.html
+++ b/public/help/zh/wiki_syntax_markdown.html
@@ -13,6 +13,7 @@
 <tr><th colspan="3">Font Styles</th></tr>
 <tr><th><img src="../../images/jstoolbar/bt_strong.png" style="border: 1px solid #bbb;" alt="Strong" /></th><td style="width:50%;">**Strong**</td><td style="width:50%;"><strong>Strong</strong></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_em.png" style="border: 1px solid #bbb;" alt="Italic" /></th><td>*Italic*</td><td><em>Italic</em></td></tr>
+<tr><th><img src="../../images/jstoolbar/bt_ins.png" style="border: 1px solid #bbb;" alt="Underline" /></th><td>_Underline_</td><td><ins>Underline</ins></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_del.png" style="border: 1px solid #bbb;" alt="Deleted" /></th><td>~~Deleted~~</td><td><del>Deleted</del></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_code.png" style="border: 1px solid #bbb;" alt="Inline Code" /></th><td>`Inline Code`</td><td><code>Inline Code</code></td></tr>
 <tr><th><img src="../../images/jstoolbar/bt_pre.png" style="border: 1px solid #bbb;" alt="Preformatted text" /></th><td>```<br />&nbsp;lines<br />&nbsp;of code<br />```</td><td>
diff --git a/public/javascripts/jstoolbar/markdown.js b/public/javascripts/jstoolbar/markdown.js
index 33a34a9c8..d087276d6 100644
--- a/public/javascripts/jstoolbar/markdown.js
+++ b/public/javascripts/jstoolbar/markdown.js
@@ -40,6 +40,15 @@ jsToolBar.prototype.elements.em = {
   }
 }
 
+// ins
+jsToolBar.prototype.elements.ins = {
+  type: 'button',
+  title: 'Underline',
+  fn: {
+    wiki: function() { this.singleTag('_') }
+  }
+}
+
 // del
 jsToolBar.prototype.elements.del = {
   type: 'button',
diff --git a/test/unit/lib/redmine/wiki_formatting/markdown_formatter_test.rb b/test/unit/lib/redmine/wiki_formatting/markdown_formatter_test.rb
index a2f864c24..54c484567 100644
--- a/test/unit/lib/redmine/wiki_formatting/markdown_formatter_test.rb
+++ b/test/unit/lib/redmine/wiki_formatting/markdown_formatter_test.rb
@@ -177,5 +177,9 @@ Nulla nunc nisi, egestas in ornare vel, posuere ac libero."]
     assert_equal Digest::MD5.hexdigest(expected), result.last, "section hash did not match"
   end
 
+  def test_should_support_underlined_text
+    text = 'This _text_ should be underlined'
+    assert_equal '<p>This <u>text</u> should be underlined</p>', @formatter.new(text).to_html.strip
+  end
   end
 end