+ added constraints for constraint-like data content, #225

      or (self.entity.oclIsUndefined() and not self.component.oclIsUndefined())

context LiteralValue

  -- Collection-like 'Content' in 'LiteralValue' 

  inv CollectionLikeContentLiteralValue ('If the \'including\' qualifier is used, directly contained \'Content\'s shall not contain a \'Value\'.' + self.toString()):

        (not self.comment->isEmpty() and self.comment->last()._body = 'including') implies

        (self.content->isEmpty() or self.content->forAll(c | c.value.oclIsUndefined()))

context Content

  -- No nested 'Content's if 'Value' is provided 

  inv ContentOrValue ('Either nested \'Content\'s or \'Value\' may be specified within \'Content\', but not both.' + self.toString()):

        self.content->isEmpty() or self.value.oclIsUndefined()

  -- Collection-like 'Content'  

  inv CollectionLikeContent ('If the \'including\' qualifier is used, directly contained \'Content\'s shall not contain a \'Value\'.' + self.toString()):

        (not self.comment->isEmpty() and self.comment->last()._body = 'including') implies

        (self.content->isEmpty() or self.content->forAll(c | c.value.oclIsUndefined()))

    --TODO: can/shall this be moved to grammar? -> probably too much of a hassle

context LiteralValueReference

  -- Referenced 'LiteralValue' visibility