anchor.diff:      :   { tagMode && !attrMode }?=> 'cond'
       ;
   
  +NAME_DEFAULT
  +    :   { tagMode && !attrMode }?=> 'default'
  +    ;
  +
   NAME
       :   { tagMode && !attrMode }?=> (UCLETTER | LCLETTER) (UCLETTER | LCLETTER | DIGIT)*
       |   { tagMode && attrMode }?=> (UCLETTER | LCLETTER) (UCLETTER | LCLETTER | DIGIT | '_' | ' ' | '?')*
  
positive.code:         | {has_ver1=1;} ver1=attr_expression_ver1
          | {has_ver2=1;} ver2=attr_expression_ver2
          | {has_cond=1;} cond=attr_expression_cond
          | anyattribute
          )*
          ( TAG_CLOSE
  
negative.code:     :   TAG_START_OPTION
          ( value=attr_int_value
          | name=attr_constant_name 
          | attr_expression_default
          | anyattribute
          )*
          ( TAG_CLOSE doc=SHORTDOC* TAG_END_OPTION
  