it seems like this will create a new revision of the DTD file... glassfish-application-client_6_0-1.dtd (or something).
Correction to earlier response: Actually, this feature has been present (in unsupported and undocumented and untested form) since 3.0 so the DTD already accounts for this.
2
enhancement
live link (not dead text) for references to JSR-56
