null reference question

(from bug 5100 just opened)
SML 4.1.1.2 Null Ref 
change
"...not to search the reference for reference scheme information items."
to
"...not to attempt to recognize any reference schemes in it."

I made that change in the bug because it pretty clearly preserves the 
original intent.  The larger question is whether or not we think that 
original intent is correctly stated.
It says not to examine null refs for ref scheme data, but later it says "
The question of whether a null reference is resolved or not is undefined; 
it is an ill-formed question."  Note that the quoted text talks 
specifically about resolution, not about parsing the reference element for 
ref scheme data.  Those could, perhaps should, be viewed as separate 
sequential processes.  In which case we need to assert whether or not it 
is an ill-formed question to ask "which ref schemes does a null ref 
contain?".
I think it would be consistent with our discussions to date to assert that 
processing of null refs should be proscribed either at parsing for schemes 
or at actual resolution once a given scheme has been identified in the 
reference.
Having flipped a coin, I'll propose we make the assertion that null 
references must not be parsed/matched for ref scheme compliance (or more 
generally, "must not attempt to recognize a null ref as being compliant w/ 
any ref scheme(s)").

Best Regards, John

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