These combinations seem to be a clear restriction of
an attributes cardinality from (0,1) to (0,0) in case 1 and to (1,1) in
As the XML Schema specification is quite complex I
rely on XSV and IBMs Schema Quality Checker to find out the valid
XSV doesn't bother about changing the attribute
through derivation by restriction - all combinations are valid.
SQC grants three combinations: case 1 and 2 and a
(3) Basetype: use="required"
This case is not restriction. (In my understanding of
So my question concerns the validity of this third
case. Is this case valid? Where is it specified in the Schema