An elementRule references to a tag via a role, and the tag may in turn reference to attPool elements. When an elementRule and a tag is so closely related, it may be convenient to merge them into a single element rather than separating them. An advantage of this style is that roles do not need names. Before this rewrite, we needed names which are different from the tag names or labels. Omission of these names enhance readability.
Some people find it attractive to describe attributes and hedge models together.
The first example uses attributes, while the second uses elements. An elementRule containing a tag may not have the role attribute. The label attribute is mandatory, instead. An embedded tag may not have the role attribute. The name attribute is permitted, but it is not present in this example.