using specified? attributes element-qualifier indexer as alias-name
     action

The using prefix can be applied to the attributes shelf in the same way that it is applied to programmer-defined shelves.

In the action following the using prefix, the selected item is referenced by the keyword attribute followed by the alias-name defined in the using prefix.

A using attributes prefix will cause input to the markup parser to be buffered until the action to which it applies completes.

If a repeat over action in the input processor iterates over a set of attributes or over the tokens of an attribute, or if an attribute or attribute token is identified by a using prefix, all text written to the #markup-parser stream will be "buffered" in the same manner.