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comments on Proposed Edited Recommendation for XML Schema Second Edition

From: Eric J. Schwarzenbach <Eric.Schwarzenbach@wrycan.com>
Date: 24 Mar 2004 07:26:02 -0700
Message-ID: <405F2021.6000003@wrycan.com>
To: www-xml-schema-comments@w3.org




My comments relate to

http://www.w3c.org/TR/2004/PER-xmlschema-1-20040318/#rcase-MapAndSum

I'd like to request that

rcase-MapAndSum.2 be rephrased to make it more readable. There are a 
number of places in the these documents that suffer the same sort of 
human-parseability problems but this sentence is particularly egregious.

The current wording is

"The pair consisting of the product of the {min occurs} of R and the 
length of its {particles} and unbounded if {max occurs} is unbounded 
otherwise the product of the {max occurs} of R and the length of its 
{particles} is a valid restriction of B's occurrence range as defined by 
Occurrence Range OK (3.9.6)."

To make sense of it, one has to mentally reconstruct the boolean logic 
from a sentence which uses no commas or other delimiters to give any 
clue how the clauses should be nested (at least one conjunction is 
ambiguous, but I think one can deduce how it must go--one should not 
have to deduce, however, it should make its meaning clear).

"The pair consisting of:
    (the product of the {min occurs} of R and the length of its {particles})
    and
    (
        (unbounded if {max occurs} is unbounded)
        otherwise
        (the product of the {max occurs}of R and the length of its 
{particles})
    )
is a valid restriction of B's occurrence range as defined by Occurrence 
Range OK (3.9.6)."

Perhaps some such formatting like I use above would help--certainly 
natural language is not very "natural" for conveying nested boolean logic.

Even having done this a few things are unclear:

What is meant by "the pair". It's become apparent to me this must mean 
an ordered
(min, max) pair.  I may be mistaken, but I don't think this document 
defines "pair" to be assumed to have this meaning.

In the phrase "unbounded if {max occurs} is unbounded", it does not 
specify  {max occurs}of what the way it does the other occurrence 
specifiers.  I believe "unbounded if {max occurs} of R is unbounded" is 
meant.

The phrase "length of its {particles}" is unclear to me. The number of 
particles? The sum of each particles min value? The sum of each 
particles max value?

The notes could also use some explication:

*"Note: *This clause is in principle more restrictive than absolutely 
necessary, but in practice will cover all the likely cases, and is much 
easier to specify than the fully general version."

It would be useful to know what cases it does not cover.

*"Note: *This case allows the 'unfolding' of iterated disjunctions into 
sequences. It may be particularly useful when the disjunction is an 
implicit one arising from the use of substitution groups."

What is an "iterated disjunction"? Or at least what does "disjunction" 
mean in this context? I only find the word used one other time in this 
document, in 2.2.3.1 Model Group.

-- 
Eric Schwarzenbach
Principal Content Architect
Wrycan, Inc
617-684-0182
Received on Wednesday, 24 March 2004 09:29:27 UTC

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