This test checks indents on block-containers and especially inheritance of start-indent over a block-container.

Since block-container generates a reference-area and no margin is specified the block-container as well as its nested block inherit the start-indent of the top-most block. Since block-container also creates a viewport the orange block is effectively indented two times by 10 pt. (See 5.3.2 in XSL 1.0)