[DFDL-WG] Fw: DFDL OGF WG call - Action 020

Thu Feb 12 07:25:33 CST 2009

Hi Mike

I think it's a simplification too far. Many people especially those with a 
mainframe or COBOL background know what a zoned decimal is. The wikipedia 
entry for binary coded decimal explicitly covers the BCD, packed & zoned 
'variants'. MRM and WTX both explicitly support zoned too. And it's easier 
to say that the 'decimalSignStyle' property applies to zoned decimals than 
to say it applies to any patterns that happen to have a P in them. On 
balance I would keep zoned as a representation.

So we need to decide whether zoned is only allowed for a signed decimal. 
There's no harm in allowing it for unsigned, just some redundancy, and it 
makes validation of the pattern against the rep easier (if something is 
zoned it can only have a subset of pattern chars).

Btw we don't need leading overpunched sign, only trailing - see my case 
for this below.

Regards

Steve Hanson
Programming Model Architect
WebSphere Message Brokers
Hursley, UK
Internet: smh at uk.ibm.com
Phone (+44)/(0) 1962-815848

"Mike Beckerle" <mbeckerle.dfdl at gmail.com> 
12/02/2009 12:51
Please respond to
<mbeckerle.dfdl at gmail.com>

To
Steve Hanson/UK/IBM at IBMGB, <dfdl-wg at ogf.org>
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Subject
RE: [DFDL-WG] Fw: DFDL OGF WG call - Action 020

This does suggest another simplification.

Zoned is so close to text....Suppose we scrap the concept of "zoned" 
altogether, and just add a character to our number pattern language to 
allow one to specify a overpunched sign digit. E.g., 

"+00000" is text
"P0000" same with overpunched leading sign. 
"00000+" text
"0000P" same with overpunched trailing sign

The decimal point would normally be implied in these,  (I still like 
having a cobol-style "V" to position this instead of separate properties 
stating the position - one of the few good features about cobol is the 
number patterns. I still think we could quite easily pre-process the "V" 
out of these strings and then hand the rest through to an ICU library as 
an implementation - however the "P" probably does need to be a change in 
that library.) 

Mike Beckerle | OGF DFDL WG Co-Chair | CTO | Oco, Inc.
Tel:  781-810-2100  | 504 Totten Pond Road, Waltham MA 02451 | 
mbeckerle.dfdl at gmail.com 

From: dfdl-wg-bounces at ogf.org [mailto:dfdl-wg-bounces at ogf.org] On Behalf 
Of Steve Hanson
Sent: Wednesday, February 11, 2009 1:34 PM
To: dfdl-wg at ogf.org
Subject: [DFDL-WG] Fw: DFDL OGF WG call - Action 020

It was noted on the call this week that there is an alternative to my 
zoned decimal overpunching proposal i) below. 

I said: 

- If it is an unsigned type then DFDL expects the rightmost byte to have a 
zone nibble when parsing, and outputs a zone nibble when unparsing. 
- If it is a signed type then DFDL expects it to have a sign nibble when 
parsing, and outputs a sign nibble when unparsing. 

But my unsigned type behaviour could be achieved by specifying a rep of 
text instead of zoned.  If that is the case, the alternative is to only 
allow zoned rep for signed decimal logical types. 

Thoughts? 

Regards

Steve Hanson
Programming Model Architect
WebSphere Message Brokers
Hursley, UK
Internet: smh at uk.ibm.com
Phone (+44)/(0) 1962-815848 
----- Forwarded by Steve Hanson/UK/IBM on 05/02/2009 10:17 ----- 
Steve Hanson/UK/IBM 
28/01/2009 13:54 

To
DFDL Working Group 
cc

Subject
DFDL OGF WG call - Action 020Link

Action 020: 
020
SH: Resolve packedDecimalSignCodes behaviour depends on NumberCheckPolicy 
22/10: No progress 
10/12: added how to decide to overpunch and sign position 

a) Resolve packedDecimalSignCodes behaviour depends on NumberCheckPolicy 

Add new property to section 15.4 Properties Specific to Number with Binary 
representation. 
binaryNumberCheckPolicy 
Enum 
Values are ?strict? and ?lax?. 
Indicates how lenient to be when parsing binary numbers. 
If ?lax? then the parser tolerates all valid alternatives where such 
alternatives exist. Specifically, for binaryNumberRepresentation = 
'packed' the sign nibble for positive, negative, unsigned and zero is 
allowed to be any of the valid respective values. 
On unparsing, the specified value is always used. 

Also suggest changing some of the other property names in 15.4: 
"decimalVirtualPoint" -> "binaryDecimalVirtualPoint" 
"packedDecimalSignCodes" -> "binaryPackedSignCodes" 

And changing binaryNumberRepresentation enumeration: 
"BCD" -> "bcd" 

b) Zoned decimals: How to decide to overpunch and sign position 

Spec assumes that overpunching of the rightmost character always takes 
place. IBM architecture allows no overpunching (ie, Fx instead of Cx/Dx) - 
this is supported by IBM MRM & WTX parsers. Additionally IBM MRM parser 
allows separate sign byte, and sign byte on left. Let's deal with these 
separately: 
i) No overpunching. 
The IBM architecture allows the rightmost byte to have a zone (Fx) or a 
sign (Cx/Dx) as the left nibble. I don't see why we can't base what to 
expect when parsing, and output when unparsing, on the logical xsd type. 
- If it is an unsigned type then DFDL expects the rightmost byte to have a 
zone nibble when parsing, and outputs a zone nibble when unparsing. 
- If it is a signed type then DFDL expects it to have a sign nibble when 
parsing, and outputs a sign nibble when unparsing. 
For analogy with DFDL packed decimals, it seems at first glance that we 
should also extend the numberCheckPolicy 'lax' setting to treat a zone 
nibble as a +ve sign nibble for a signed type. However, IBM iSeries always 
outputs Fx to mean +ve but accepts both Fx & Cx on input. It is perhaps 
better therefore that DFDL always tolerates Fx when parsing a signed zoned 
decimal, otherwise iSeries users would always have to set 
numberCheckPolicy to 'lax', which might have other implications in the 
future. 
ii) Separate sign byte. 
I don't believe the IBM architecture allows this. I don't think DFDL needs 
to support it. MRM has this, but I think it's because early on MRM did not 
explicitly support text decimals as such, just COBOL variations, and it 
was easier just to call them all zoned. 
iii) Sign byte on left. 
I don't believe the IBM architecture allows this. I don't think DFDL needs 
to support it.  MRM has this, but for the same reason as ii) 

Conclusion: No new DFDL properties needed, but words need adding to 
explain zoned parse/unparse behaviour better. 

Also suggest changing property names: 
"zonedDecimalSignStyle" -> "numberZonedSignStyle" 
"zeroNumberRep" -> "numberZeroRep" 

Should also make clear that any explicit negative pattern in numberPattern 
will be ignored if the xsd type is unsigned. (We could make this an error 
but it precludes creation of a textNumberFormat that works with both 
signed and unsigned types, plus pattern  "##0.0" implictly is equivalent 
to "##0.0;(##0.0)" ). 

Regards

Steve Hanson
Programming Model Architect
WebSphere Message Brokers
Hursley, UK
Internet: smh at uk.ibm.com
Phone (+44)/(0) 1962-815848 

Alan Powell/UK/IBM at IBMGB 
Sent by: dfdl-wg-bounces at ogf.org 
23/01/2009 13:36 

To
dfdl-wg at ogf.org 
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Subject
[DFDL-WG] DFDL: Minutes from OGF WG call, 21 January 2009

Open Grid Forum: Data Format Description Language Working Group

Weekly Working Group Conference Call
14:00 GMT, 21 January 2009

Attendees 
Alan Powell (IBM) 
Mike Beckerle(Oco) 

Apologies 
Steve Hanson (IBM) 

1. XSD 1.1 
Deferred to next call 

2. Calendar formats 
Discussed updated (v4) supplement emailed by AP 

Agreed millisec/secSinceEpoc cannot be implied by length of logical data 
so need seperate enumerations. Observed that these options were really 
combination of 3 properties  binary, length and sec/millisec.  Suggested 
renaming to binarySeconds and binaryMilliseconds 

Packed calendars: decided that need to be able to specify at least the 
packedDecimalSignCodes property rather than assuming a default so 
reference will be added to calendar description 

Locale needs to be specified  for numberformats and calendarFormats 
(didn't identify any other areas) as it modifies the behaviour of ICU. 
Decided to add  locale to numberFormat and CalendarFormat 

3. Escape Schemes 

Agreed need for multiple escape delimiter pairs but not nested. 
Need an escape for escape character even though in most cases this will be 
the same character, eg /n //, There are some formats that have a different 
escape, eg /n &/. Only need single escape characters and one level of 
escape characters. 
Discussed how to deal with comments of the form   /*  comment */  where 
the escape delimiters  are also the initiator and terminator of the field. 
Semantic needed is 'only look for field terminator not any parent 
terminator or any other syntax elements'. May fall out naturally from the 
speculative parsing rules. Need further discussion. 

4. AOB 
Next call 28 January 14:00 

Meeting closed, 15:00 GMT 

Actions raised at this meeting 
No
Action 
031

Current Actions: 
No
Action 

012
AP/SH: Update decimalCalendarScheme 
10/9: Not allocated yet 
17/9: No update 
24/9: Add calendar binary formats to actions 
22/10: No progress 
16/1: proposal distributed and discussed. Will be redistributed 
21/1: add locale, 

020
SH: Resolve packedDecimalSignCodes behaviour depends on NumberCheckPolicy 
22/10: No progress 
10/12: added how to decide to overpunch and sign position 
023
MB: Review Schema 1.1 
024
String XML type 
025
Escape schemes 
21/1: discussed requirements 
026
SH: Envelopes and Payloads 
027
Property precedence tables 
028
Variable markup 
029
 valueCalc (output length calculation) 
030
AP: confirm with WTX that can drop duration 
21/6: WTX confirm that they do not have a duration type so do not need it 
in dfdl. Will drop from spec. Closed 

Closed actions: 
030
AP: confirm with WTX that can drop duration 
21/6: WTX confirm that they do not have a duration type so do not need it 
in dfdl. Will drop from spec. Closed 

034 Work items: 
No
Item 

001
String XML type (Ian P) - Apr 30, 2008 

002
Escape schemes (Ian P) - Apr 30, 2008 

003
Variables - ??, 2008 (Mike) 

005
Improvements on property descriptions - ??, 2008 (All - split TBD) 

006
Envelopes and Payloads (Steve) - Apr 30, 2008 

007
(from draft 32) valueCalc (Mike) - ??, 2008   
mostly 
complete 
008
(from draft 32) Property precedence for writing (Steve) - 
under review 
009
(from draft 32) Variable markup (Steve) - Mar 31, 2008   
proposal needs writing up 
010
(from draft 32) Assertions, discriminators and choice, including 
discussion of timing option (Suman) - Mar 31, 2008 * in progress * 

011
(from draft 32) How speculative parsing works (combining choice and 
variable-occurence - currently these are separate) ??, 2008 (IBM) 
 in progress 
012
(from draft 32) Reordering the properties discussion: move representation 
earlier, improve flow of topics ??, 2008 (Alan) * not started * 

025
Augmented infoset and unparsing (Alan)   
added but needs work
complete - specification updated 

Alan Powell

MP 211, IBM UK Labs, Hursley,  Winchester, SO21 2JN, England
Notes Id: Alan Powell/UK/IBM     email: alan_powell at uk.ibm.com 
Tel: +44 (0)1962 815073                  Fax: +44 (0)1962 816898

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