4 JCK tests (idI021.xsd, idJ029.xsd schema attached) use the xpath expression '. //.' in a selector and in a field.

Although the specification (http://www.w3.org/TR/xmlschema-1/#coss-identity-constraint) states:
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For readability, whitespace may be used in selector XPath expressions even though not explicitly allowed by the grammar:
whitespace may be freely added within patterns before or after any token.
...
Lexical productions
[5] token ::= '.' | '/' | '//' | '|' | '@' | NameTest
[6] whitespace ::= (#x20 | #x9 | #xD | #xA)+
When tokenizing, the longest possible token is always returned.
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The parser ( schemaFactory.newSchema( schemaSources ) ) fails with exception
c-general-xpath: The expression '. //.' is not valid with respect to the XPath subset supported by XML Schema.