From my sojourn with XML and Schema validation, it seems that when fragment-level conformance is enabled for an XMLReader instance, the XML source stops being validated against any included Schemas.
However I cannot verify this from the MSDN documentation as it doesn't seem to describe XSD Schema behaviour in light of conformance level. Also if I assume this problem is true, I cannot find a workaround for it.
I would like to know how to validate a XML fragment against an XSD Schema.
In my case I'm validating against the XHTML 1 Strict Schema. By the fact deprecated HTML tags like <center> are not being flagged as invalid, this is part of the reason I believe fragment conformance ignores schema. Also when I use document-level conformance in the same scenario, validity errors are successfully flagged.
For a code sample of the type of validation scenario I'm using see this.