anchor.diff:          (HEADER_XML SHORTDOC*)? // not really required, but usually present
           (HEADER_DOCTYPE SHORTDOC*)? // not really required, but usually present
           t=TAG_START_ROOT anyattribute* TAG_CLOSE SHORTDOC*
  -        declarations
  +        declarations?
           TAG_END_ROOT SHORTDOC*
           EOF
           -> 
  
positive.code:                ^(FIELDDEF DOC TYPENAME[$t, "Int64"] VARIABLENAME[$t, "user1"])
                 ^(FIELDDEF DOC TYPENAME[$t, "Int64"] VARIABLENAME[$t, "user2"])
             )
             declarations
      ;
  
  // extra attributes that we throw away
  
negative.code:     ;
  
  declarations
      :   (versiondefine | basicdefine | enumdefine | structdefine | bitflagsdefine)+
      ;
  
  versiondefine
  