[DFDL-WG] Padding to Minimum length proposal and Implicit lengths

Wed Dec 10 07:52:55 CST 2008

Mike - missing brackets - should be "(totaldigits+1)/2"

Alan - I see what you have done - you've added textStringPad but also made 
it the controlling property - ie, you look at textStringPad first. (This 
matches what IBM WTX does). That's ok - as long as you don't have 
textStringPad controlling trimming. So here's a proposal that reflects 
that. Note that I have made textPadKind applicable to strings, numbers and 
calendars (like textTrimKind) - I think it's the justification direction 
and the pad char that vary per type, not whether to pad or not.  I've also 
dropped the stuff about a length prefixed string being trimmed to a max 
length - we can re-instate in the appropriate place if needed - was that 
to do with ensuring you couldn't pass a string whose length could not be 
accomodated in the prefix type (because that's not how it was worded).

Property Name 
Description 
textTrimKind
Enum
Valid values ?none?, ?padChar?
Indicates whether to trim data on input. 
'none': No trimming takes place
'padChar': If lengthKind results in a fixed length then the padding 
character can be trimmed instead, as controlled by 
textStringJustification. 
Annotation: dfdl:element (simple type ?string?)
textPadKind
Enum 
Valid values  ?none?,  ?fixed?, ?minimum'
Indicates whether to pad data on output.
?none?: The string is expected to match the length, it is an error 
otherwise.
'fixed': If lengthKind results in a fixed length then the data can be 
padded to the fixed length, as controlled by textStringJustification.
'minimum': If lengthKind results in a fixed length then the data can be 
padded to the length given by dfdl:outputMinLength property, as controlled 
by textStringJustification.

Property Name 
Description 
textStringJustification 
Enum 
Valid values ?left?, ?right?,  ?center? 
Output:
'left': Justifies to the left and adds padding chars to the string 
contents if the string is too short, to the length determined by the 
textPadKind property. 
'right': Justifies to the right and adds padding chars to the string 
contents if the string is too short, to the length determined by the 
textPadKind property.
?center?: Adds equal padding chars left and right of the string contents 
if the string is too short, to the length determined by the textPadKind 
property. It adds one extra padding char before if needed.
Input:
'left': Trims any padding characters from the right of the string, 
according to textTrimKind property.
'right': Trims any padding characters from the left of the string, 
according to textTrimKind property.
?center? Trims any padding characters from the left and right of the 
string, according to textTrimKind property. 
 [OMG/CAM property justification] 
Annotation: dfdl:element (simple type ?string?) 

Regards

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

DFDL <mbeckerle.dfdl at gmail.com> 
Sent by: dfdl-wg-bounces at ogf.org
09/12/2008 19:24

To
Alan Powell/UK/IBM at IBMGB
cc
"dfdl-wg at ogf.org" <dfdl-wg at ogf.org>
Subject
Re: [DFDL-WG] Padding to Minimum length proposal and Implicit   lengths

In the table I didn't understand the "totaldigits+1/2" 

...mikeb

On Dec 9, 2008, at 1:33 PM, Alan Powell <alan_powell at uk.ibm.com> wrote:

Mike, Steve 

The proposal to allow padding to minimum length on output consists of 
new property ouputMinLength 
Separate pad properties for string, number and calendar types 
new textxxxxPad property to control padding . Moved from from 
textxxxxxxJustification
1        Padding 

Property Name 
Description 
outputMinLength 
String.   
Only used when textStringPad, textNumberPad or textCalendarPad is 
?minlength?. 
Specifies the minimum output length of this element using either a fixed 
number or an expression to refer to an element earlier in the data,. 
Annotation: dfdl:element (all simple types)
1.1        Properties Specific to Strings with Text representation 

Property Name 
Description 
textStringPad 
Enum 
Valid values  ?none?,  ?fixed?, ?minLength? 
Controls how an item is justified on output when the actual length of a 
text string is different from the specified length. 
Controls how an item is trimmed on input if  textTrimKind is padChar 
If ?none? the string is expected to match the length. 
Otherwise: 
- If lengthKind results in a fixed length: If shorter than the specified 
length it is padded with the pad character. If longer than the specified 
length it is truncated. 
- If lengthKind is ?prefixed?: If the string is longer than any specified 
maximum length it is truncated. 
textStringJustification 
Enum 
Valid values ?left?, ?right?,  ?center? 
 ?center? adds equal padChars before and after the string contents if the 
string is too short. It adds one extra padChar before if needed. 
?center? truncates equal numbers of characters before and after if the 
string is too long. It removes one extra character at the front of the 
string if needed. 
 [OMG/CAM property justification] 
Annotation: dfdl:element (simple type ?string?) 
textStringPadCharacter 
String. 
The padding character used as the default for justification of text 
elements. 
In fixed width character sets this must contain a full single character 
representation. So if hex entities are used, enough hex bytes must be 
supplied to provided the full width of a character. 
In variable width character sets, this character must be a minimum-width 
character unless it is specified as an entity (see section TBD Entities) 
Annotation: dfdl:element (simple type ?string?)
1.2        Properties Specific to Number with Text representation 

Property Name 
Description 
textNumberPad 
Enum 
Valid values  ?none?,  ?fixed?, ?minLength? 
Controls how an item is justified on output when the actual length of a 
text string is different from the specified length. 
Controls how an item is trimmed on input if  textTrimKind is padChar 
If ?none? the string is expected to match the length. 
Otherwise: 
- If lengthKind results in a fixed length: If shorter than the specified 
length it is padded with the pad character. If longer than the specified 
length it is truncated. 
- If lengthKind is ?prefixed?: If the string is longer than any specified 
maximum length it is truncated. 
textNumberJustification 
Enum 
Valid values ?left?, ?right?,  ?center? 
 ?center? adds equal padChars before and after the string contents if the 
string is too short. It adds one extra padChar before if needed. 
?center? truncates equal numbers of characters before and after if the 
string is too long. It removes one extra character at the front of the 
string if needed. 
 [OMG/CAM property justification] 
Annotation: dfdl:element (simple type ?string?) 
textNumberPadCharacter 
String. 
The padding character used as the default for justification of text 
elements. 
In fixed width character sets this must contain a full single character 
representation. So if hex entities are used, enough hex bytes must be 
supplied to provided the full width of a character. 
In variable width character sets, this character must be a minimum-width 
character unless it is specified as an entity (see section TBD Entities) 
Annotation: dfdl:element (simple type ?string?)
1.3        Properties Specific to Calendar  with Text representation 

Property Name 
Description 
textCalendarPad 
Enum 
Valid values  ?none?,  ?fixed?, ?minLength? 
Controls how an item is justified on output when the actual length of a 
text string is different from the specified length. 
Controls how an item is trimmed on input if  textTrimKind is padChar 
If ?none? the string is expected to match the length. 
Otherwise: 
- If lengthKind results in a fixed length: If shorter than the specified 
length it is padded with the pad character. If longer than the specified 
length it is truncated. 
- If lengthKind is ?prefixed?: If the string is longer than any specified 
maximum length it is truncated. 
textCalendarJustification 
Enum 
Valid values ?left?, ?right?,  ?center? 
 ?center? adds equal padChars before and after the string contents if the 
string is too short. It adds one extra padChar before if needed. 
?center? truncates equal numbers of characters before and after if the 
string is too long. It removes one extra character at the front of the 
string if needed. 
 [OMG/CAM property justification] 
Annotation: dfdl:element (simple type ?string?) 
textCalendarPadCharacter 
String. 
The padding character used as the default for justification of text 
elements. 
In fixed width character sets this must contain a full single character 
representation. So if hex entities are used, enough hex bytes must be 
supplied to provided the full width of a character. 
In variable width character sets, this character must be a minimum-width 
character unless it is specified as an entity (see section TBD Entities) 
Annotation: dfdl:element (simple type ?string?)

I also completed the table of meaning of implicit lengths for different 
types 

1.1        Lengths of simple types for lengthKind=implicit 

Implemented in WMB GUI helper function 

Simple type 
text (+ xml) 
binary 

String 
Length/maxlength 
n/a 

Float 
Text: numberPattern
(length of positive subpattern) 
Zoned: TotalDigits 
32 

Double 
Text: numberPattern 
Zoned: TotalDigits 
64 

Decimal/Integer 
Text: numberPattern 
Zoned: TotalDigits 
Pkd/bcd: TotalDigits+1/2 

Long, UnsignedLong 
Text: numberPattern 
Zoned: 19 
binary: 64 
Pkd/bcd: TotalDigits+1/2 

Int, Unsignedint 
Text: numberPattern 
Zoned: 10 
binary: 32 
Pkd/bcd: TotalDigits+1/2 

Short, Unsignedshort 
Text: numberPattern 
Zoned: 5 
binary: 16 
Pkd/bcd: TotalDigits+1/2 

Byte, Unsignedbyte 
Text: numberPattern 
Zoned: 3 
binary: 8 
Pkd/bcd: TotalDigits+1/2 

DateTime 
Calendarpattern 

Date 
Calendarpattern 

Time 
Calendarpattern 

Duration 
Calendarpattern 

Boolean 
Length of  textBooleanTrue 
32 

HexBinary 
n/a 
Length/maxlength 

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

Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 
741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU 

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