References to XML Schema Specification
The same as in editing XML documents, the message of an error obtained by validation of an XML Schema document includes a reference to the W3C specification for XML Schema. An error message contains an Info field that will open the browser on the "XML Schema Part 1:Structures" specification at exactly the point where the error is described, thus allowing you to understand the reason for that error.
Link to Specification for XML Schema Errors

Validation of an XML Schema containing a type definition with a minOccurs or
            maxOccurs attribute having a value larger than 256 limits the value to 256
            and issues a warning about this restriction in the Message panel at the bottom of
            the Oxygen XML Editor window. Otherwise, for large values of the minOccurs and
            maxOccurs attributes, the validator fails with an OutOfMemory
            error that might make Oxygen XML Editor unusable without restarting the entire
            application.
         
