[DFDL-WG] Behavior of nilKind literalValue with respect to binaryNumberRep of packed

[Mike Beckerle]

Can you give what the bytes look like for typical values of various sizes
small and large,  how their length is determined, and what a nil value
looks like in bytes?


Mike Beckerle | OGF DFDL Workgroup Co-Chair | Owl Cyber Defense |
www.owlcyberdefense.com
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On Tue, Apr 14, 2020 at 4:54 PM Bradd Kadlecik <braddk at us.ibm.com> wrote:

> Yes that works for fixed length but not variable length which is possible
> for packed decimal with bigEndian.
>
>
> Regards,
>
> *Bradd Kadlecik*
> z/TPF Development
> ------------------------------
> *Phone:* 1-845-433-1573
> *E-mail:* *braddk at us.ibm.com* <braddk at us.ibm.com>
> 2455 South Rd
> Poughkeepsie, NY 12601-5400
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>
>
> [image: Inactive hide details for Mike Beckerle ---04/14/2020 03:56:45
> PM---Not sure I understand the mixture of the concepts of justif]Mike
> Beckerle ---04/14/2020 03:56:45 PM---Not sure I understand the mixture of
> the concepts of justification and packed decimal here.
>
> From: Mike Beckerle <mbeckerle.dfdl at gmail.com>
> To: Bradd Kadlecik <braddk at us.ibm.com>, DFDL-WG <dfdl-wg at ogf.org>
> Date: 04/14/2020 03:56 PM
> Subject: [EXTERNAL] Re: [DFDL-WG] Behavior of nilKind literalValue with
> respect to binaryNumberRep of packed
>
> ------------------------------
>
>
>
>
> Not sure I understand the mixture of the concepts of justification and
> packed decimal here.
>
> I usually think of packed decimal as fixed length and without padding.
>
> Let me assume this example: 12345C is value 12345, 00000C is zero, and
> 00000F is the nil indicator.
>
> So, bigEndian byte order, I think dfdl:nilvalue="%#r00;%#r00;%#r0F;" is
> what I'd expect to see for a literalValue nilValue to match that.
>
> I'm guessing some assumption in the above doesn't match your use case, so
> please correct.
>
> Mike Beckerle | OGF DFDL Workgroup Co-Chair | Owl Cyber Defense |
> *www.owlcyberdefense.com* <http://www.owlcyberdefense.com>
> Please note: Contributions to the DFDL Workgroup's email discussions are
> subject to the *OGF Intellectual Property Policy*
> <http://www.ogf.org/About/abt_policies.php>
>
>
>
> On Tue, Apr 14, 2020 at 2:59 PM Bradd Kadlecik <*braddk at us.ibm.com*
> <braddk at us.ibm.com>> wrote:
>
>    I think there is a problem when the literalValue is left-justified for
>    binary data such as packed decimals. This seems problematic because a "0"
>    value might be indicated by having the last byte be 0x0C for a signed
>    numeric while a nil value might be desired to be understood by having the
>    last byte be a 0x0F. In both cases, all preceding bytes are 0x00. In the
>    case that the packed decimal is of variable length, there seems no way to
>    represent this nil value unless it is understood that the fillByte is used
>    for the area preceding the NilElementLiteralContent. Apologies if I might
>    of missed some clarification made regarding this.
>
>
> Regards,
>
> *Bradd Kadlecik*
> z/TPF Development
> ------------------------------
> *Phone:* 1-845-433-1573
> *E-mail:* *braddk at us.ibm.com* <braddk at us.ibm.com>
> 2455 South Rd
> Poughkeepsie, NY 12601-5400
> United States
>
>
>
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