RE: [xml-dev] What does "optional" mean?

["Costello, Roger L." <costello@mitre.org>]

Thanks to all who participated in this discussion -- David C, Mukul, David L, Len, Dan, Michael, Jim, John, and Ken.

Fascinating discussion!

For me the discussion has been a great reminder:

     Schemas don't have any semantics. 

I think that is something that bears repeating often.

I particularly like Jim Melton's definition of "optional":

    Optional, in XML Schemas, in DTDs, and other 
    XML-related standards (at least within the W3C)
    means nothing more than "may be provided or 
    omitted".

and he goes on to say:
  
    Any "semantics" associated with the  provision 
    or omission of something optional might  be 
    provided by an application or other environment.

Awesome clarity!

At this point I will do my best at characterizing what I think Walter Perry would say: 

    The consumer of an XML instance document that
    has an omitted element or attribute is free to give
    whatever meaning he or she desires to that omission.

[Walter, if I have not accurately characterized your ideas please correct me.]

/Roger