Bindings in the DESCRIBE clause

Hello

Any reason why bindings in the DESCRIBE clause using expressions is not permitted in SPARQL 1.1, when they are permitted in the SELECT clause?

Compare [11] and [9] in:
http://www.w3.org/TR/sparql11-query/#sparqlGrammar

Example: Describe the first iri that is well defined, using the COALESCE function.

This could be done using BIND [62], but a SPARQL user would expect syntax to be consistent.

Sincerely,
Peter Waher