Issue 6404 - use of "whatever"

This issue is about defining the MEX dialect and defining what gets returned.

http://www.w3.org/Bugs/Public/show_bug.cgi?id=6404

In particular, I was asked to provide an example of why it might be useful, in the case where no dialect is specified in the GetMetadata request, for the service itself to be able to decide what it would return (the so-called "whatever" case).  The other option would be for this case to return all MEX sections.

The best example I can provide for the "whatever" case is this:

If the MEX specification gets "profiled" for a specific purpose, it would be very useful to allow the profile to be able to specify what metadata is to be returned in this default case (especially the non-MEX defined metadata sections).  If you do not do this then each profile would have to define some separate dialect to mean "give me all the metadata within my profile".  Thus the default case gives you an over-loadable definition of "all" or perhaps "normal", which can include non-MEX defined sections.

In a typical profiled case:
Nothing = "return all metadata within my profile"
MEX = "return all MEX dialects"

If it is not a profiled implementation, the spec could be recommend that the implementation return:
Nothing = MEX = "return all MEX dialects"