Hi all once more,

if there is a problem of messy schema or complexity of this approach for developers, it is possible to add "processing" validation layer using Schematron or XSLT template - simply by adding the Schematron or XSLT code to xs:appinfo element of schema documentation. The application can parse schema, read code and execute it and report results of additional validation to user (or to some process).

To catch such problems by Schematron or XSLT is deadly simple. And more, we can meet worse problems, where the XML schema is absolutely unusable - for example, dependence "if element A has value X, then value of element B must fall between Y and Z". In such case, Schematron and XSLT approach is only possible. Moreover, it is possible to include all such dependencies into one Schematron/XSLT code.

Pavel Benda Czech Collection of Microorganisms pavelben@sendme.cz