This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
The schema for the Microsoft Element test (group="elemZ027_c";name="elemZ027_c") is described as invalid in the metadata. I think that this schema is actually valid. From my reading of the spec [1] and this post to the xmlschema-dev list [2] I believe that the block="substitution" on element "b" only blocks "a" from being a member of "b"'s substitution group. As such the element "d" specified in the base type can be substituted by "c", "b" and "a" which means the derived type is valid. [1] http://www.w3.org/TR/xmlschema-1/#cos-equiv-derived-ok-rec [2] http://lists.w3.org/Archives/Public/xmlschema-dev/2007Jan/0068.html
I fear you are right, despite the fact that the spec here is clearly bizarre. I rather like MSMcQ's attempt to find a rationale: "Er. Ah. Those who favored the current design argued that it would be more useful this way". Actually, I am not sure I have ever seen block="substitution" used in a real live schema; it appears to be pretty useless either way. But conformance often means doing things that are patently bonkers...
Looks like expected should just be flipped