Uniface uses DTD for the description of a XML. This sounds very old fashioned and has some disadvantages. I know the support of XSD is a major challenge for Uniface because XSD allows nonrelational structures. But I think even a partial support is better than no support at all.
Something simple like xmlload/xsd XMLVariable, XSDName To fix the non-relational structure, perhaps a (implicit) component could be created from the XSD. In this component all complextypes are represented as nondb-entities. The programmer has to put the functionality in this component.
The lack of XSD support is a very big disadvantage of Uniface. Only supporting DTD makes it look oldfashioned. I know it is possible to create a DTD from a XSD, but even than Uniface is not always able to handle it. For instance if there are duplicate elementnames.