[Bug 5564] recursive definition of DerefExpr should be restored

http://www.w3.org/Bugs/Public/show_bug.cgi?id=5564

           Summary: recursive definition of DerefExpr should be restored
           Product: SML
           Version: LC
          Platform: PC
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Core
        AssignedTo: cmsmcq@w3.org
        ReportedBy: kumarp@microsoft.com
         QAContact: public-sml@w3.org


It seems that DerefExpr is no longer recursively defined in section 5.2.1.2.

The definition in LC draft is:
DerefExpr ::= (NCName ':')? 'deref(' Step ('/'Step)* ')'  ('/'Step)* 

definition as in second public draft:
DerefExpr ::= (NCName ':')? 'deref(' Step (/Step)* ')'  ('/'Step)* |
              (NCName ':')? 'deref(' DerefExpr ')' (/Step)*

The definition was made incorrect sometime between second the third public
drafts. The correct definition should be restored. This may also be a potential
cause of Henry's question in bug# 5526 (What does "nested to any depth" mean?).