[DFDL-WG] Fw: One email or a flock or... - re: 10.03 draft - open review items

[Steve Hanson]

For discussion on today's call

Regards

Steve Hanson
Architect, Data Format Description Language (DFDL)
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848
----- Forwarded by Steve Hanson/UK/IBM on 16/10/2012 13:13 -----

From:   Mike Beckerle <mbeckerle.dfdl at gmail.com>
To:     Steve Hanson/UK/IBM at IBMGB
Date:   02/10/2012 18:41
Subject:        One email or a flock or... - re: 10.03 draft - open review 
items



Steve,

I've got the issues below left after your review pass on 10.03, minus 2 I 
send emails to you about separately.

Should I issue this email to the WG, or do you want me to decompose this 
into separate emails, or do you just want to list these as agenda topics 
for next call? I think it is good if people get to look at them in advance 
of a call. 

...mikeb

--------------------------------------------------------

This is a list of items left open after a review pass by SMH(on draft in 
preparation r010.03).

These items need specific WG discussion on a call. They may be small 
enough to resolve there, or may be escalated into action items. (A couple 
issues already clearly action-item related are not listed here.)

Note: please Ignore the identifiers like SMH107 or m236 I'm tagging these 
with. Those are just for me editing the text. (Those change ...grrr... if 
someone inserts a comment into the document, so they're not good issue 
identifiers).

1.      SMH107   Spec says: When the separator and terminator on a group 
have the same value, then at a point where either separator or terminator 
could be found, the separator is tried first.
Issue is that this language still feels ambiguous. E.g., So it tries the 
separator first, let’s say it finds it. Will a subsequent processing error 
cause it to backtrack and revisit this and try the terminator? Or does 
finding the separator confirm that it IS a separator, resolve forever that 
point of uncertainty? I believe the latter is what was intended (delimiter 
decisions drive parsing and are not revisited), but we need to state this 
(or do we somewhere else already?)
2.      SMH169 - Some numeric types are signed, others unsigned. Some 
representations are sign-capable, some are not (BCD specifically). Right 
now spec draft says you can't have bcd as rep for signed integer types 
long, int, short, byte. But you CAN have bcd for rep of decimal, integer. 
We could allow bcd only for nonNegativeInteger type, but there is no 
nonNegativeDecimal type, so....how to resolve? I would suggest that we 
simply allow bcd as rep for both signed and unsigned types, and it's a 
processing error to unparse a negative value into bcd rep.
3.      m229 - textStandardZeroRep - should this allow %ES; as one of the 
list of possibles?
4.      m236 - is V (virtual decimal point position) and also P allowed in 
the textNumberPattern for double and float types? 
5.      m237 - Do we check that the various symbols used for infinity, 
digits, grouping separators, decimal separators are properly distinct to 
allow parsing? E.g., that the decimal separator and grouping separator 
aren't the same, and that the positive and negative pattern variants are 
distinguishable? ICU library supposedly doesn't do this checking. Do we 
state this is an SDE in DFDL. If so then is this checking required? Can we 
make it possible for implementations to not check somehow? Other grammar 
ambiguity situations like separator and terminator being ambiguous are 
specifically NOT checked for, because determining if a grammar is 
ambiguous is hard or undecidable, and would have to be done at runtime 
because delimiters can be run-time computed. Buf for the syntax components 
of text numbers do we require checking or not?
6.      m370 - multiple PoU resolutions: If you have initiatedContent, AND 
a choiceBranchRef, AND a discriminator all on the same element, and there 
are 3 enclosing nested PoU, which one controls which? Precedence is the 
issue. Or..... do we really need to allow this? Why don’t we just disallow 
this kind of piling-on of complexity and make the user choose which PoU 
resolution technique they want?
7.      m396 - is BCD representation a mandatory feature, or optional?
8.      m398 - portability at risk if subset processors ignore properties 
they don't implement. We relaxed this from a more rigid policy, and now 
allow subsets to not validate properties they don't implement. However, is 
there a better compromise, e.g., require a warning about all 
unimplemented/unrecognized properties? E.g., dfdl:textBiDi='no' yields SDE 
"unrecognized property 'textBiDi' with value 'no'.

-- 
Mike Beckerle | OGF DFDL WG Co-Chair 
Tel:  781-330-0412

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