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[Bug 5151] pseudo-normative qualifications used in apparently normative contexts

From: <bugzilla@farnsworth.w3.org>
Date: Fri, 09 May 2008 18:44:58 +0000
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To: www-xml-schema-comments@w3.org
Message-Id: <E1JuXaU-0002vg-B3@farnsworth.w3.org>

http://www.w3.org/Bugs/Public/show_bug.cgi?id=5151





------- Comment #4 from johnarwe@us.ibm.com  2008-05-09 18:44 -------
3 Properties in the PSVI

Your argument seems "strange" given the context.  Expanding the excerpt ever so
slightly, in 3.1.1 we find:

"Any property not defined as optional is always present; optional properties
which are not present are taken to have ·absent· as their value. 
 Any property identified as a having a set, subset or list value may have an
empty value unless this is explicitly ruled out: this is not the same as
·absent·. 
 Any property value identified as a superset or subset of some set may be equal
to that set,"

Thus, in the already existing text, sentence 1 shies away from RFC 2119
vocabulary while both of the next two sentences, I think describing the same
PSVI, use RFC 2119-style MAYs.  This seems inconsistent.

4 "One of the following"

> saying "at least one" or "exactly one" suggests that more than one
> of the items in the following list might be true.  When that is not
> the case, the extra words would be misleading or confusing.

Quite true.  I am fine with, and to some level expected, that the wording would
be case-specific.  3 eyebrow hairs of concern arise at "fairly obvious that the
items are mutually exclusive", since "fairly obvious" is Eye of the Beholder
territory.  Most readers of the spec will not have the wg's level of intimate
familiarity with the content.  My lowest-cost fix would be to state in 1.5 that
in cases where the authors believe the list items to be mutually exclusive,
[this language] has been used.  While the authors are most likely right when
assessing whether a set of options falls into the ==1, >=1, 0 or 1 sorts of
categories, that is still their assessment (dare I say assertion) and hence it
may be wrong, however unlikely.

5 MUST vs "is" or "apply" ...

We simply read the suggested words to mean different things.  I mentally append
"in order for the constraint to be met" after each of these, which is for most
humans functionally equivalent to "in order for the 'thing' to be valid".  So,
for me, they are still contingent.  If we want to reduce this down to modal
logic, I think by definition you've just lost the majority of humans
(regardless of how correct doing so might be).  Taking the first citation as a
concrete example:

Schema Representation Constraint: Attribute Declaration Representation OK
In addition to the conditions imposed on <attribute> element information items
by the schema for schema documents, all of the following also apply:

Cinching down the language lawyer hat, I have to ask what "apply" even means. 
Allowing for a bit more cranial circulation, I think the intent is one (or
both, to me they are essentially the same) of the following:

(1) In addition to the conditions imposed on <attribute> element information
items by the schema for schema documents, all of the following conditions also
are imposed:

(2) In addition to the conditions imposed on <attribute> element information
items by the schema for schema documents, all of the following conditions also
must be tested:

Either of those would, to me, be an improvement.  I will not lay down in the
tracks over it however.

7 The appropriate case

"In this case, it's clear on examination that only one of the items can be true
at a time."

Kind of you to prove my point for me.  In certain languages with "case", an
otherwise is ALWAYS executed unless the individual when/if tests contain a
"break".  It is exactly this potential difference in assumptions I was pointing
out.
Received on Friday, 9 May 2008 18:45:32 GMT

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