Re: [ubl-lcsc] Re: Position Paper on List Containers

["Anthony B. Coates" <abcoates@londonmarketsystems.com>]

** Reply to message from Tim McGrath <tmcgrath@portcomm.com.au> on Sat, 30 Aug
2003 13:53:11 +0800

> a point i could add 
> when using selective list containers is that we also create a problem 
> where implementators cannot immediately identify which structures have 
> list containers and which don't, e.g. "does BasePrice have a list?" or 
> worse still "does BasePrice have a list within Invoice?"

Well, this problem exists either way.  Even without the "do I use a list"
question, you have the "how many of these can I have" question.  As usual, this
is only a problem when using Notepad or vi.  There are enough XML editors
around with "pop-up" prompting of allowable elements for the current cursor
position.  In many cases, developers will just set up their template once and
then work from that.

> Finally, i note with interest your comment about 'annotations' and urge 
> you to bring these to the attention of the NDR group( if you have not 
> already).

This is something I only realised from reading your document, so I have not had
a chance to mention it to NDR.  I would be interesting to mention it during the
joint meeting (note I will only be there for Tuesday, as I have MDDL meetings
on Wednesday).

> They are currently debating which flavour of annotation 
> (documentation or appinfo) we should use.  you are are suggested both 
> are irrelevant ! or is that just for 'reference' (which i confess to not 
> understanding)

Just for "reference".  To explain what I mean by that, in an XML Schema, when
you define a global element, you use <element name="..." ...>...</element>. 
You can have an annotation inside this, describing the element from a global
perspective.  If it is a <Tax> element, you might describe something about tax.
When you want to use your global element definition somewhere, you write
<element ref="..." ...>...</element>.  Usually there is nothing between the
open and closing tags, but according to the XML Schema spec, you can also have
an annotation here.  This is the "reference" case I was talking about.  It
allows you to annotate an occurrence of <Tax> inside <Federal> differently to
an occurrence of <Tax> inside <State>.  My point was that annotation of
references is not widely used, and not well supported by tools (some of which
normalise those annotations back to the <element name=...> definition,
unhelpfully).

> We have stated the the schema is the only normative 
> form of UBL and so I dont see how we can avoid this information being in 
> there.  But seriously, are we going to be guided by TurboXML? i know 
> that sounds fatuous but in the history of design we sometimes have to 
> take a lead.

Well, seriously, I find it hard to believe that UBL is afraid to use Schema
appinfo, but that is what has happened.  The fact that UBL Schemas will be
altered significantly if opened and saved by a popular XML Schema editor is, to
my mind, a far greater and more real concern.  I'm not opposed to UBL taking a
leadership position, but not arbitrarily.  I can't see why UBL would be brave
on this and cowardly on appinfo.

> Regardless of that issue, the point of concern here is not our 
> "difficulty of making annotations relevant to all usages when they are 
> attached to a global definition" - it is that each usage needs its own 
> global definition.  rather like your comment about AddressLine0-7List 
> and AddressLine1-3List,  my point is that we need different list 
> defintions for each usage (i.e. AllowanceChargeTaxCategoryList is not 
> the same as ItemTaxCategoryList).

This doesn't suggest any kind of problem with lists, though, it simply points
out that one of the naming rules has the wrong effect when applied to lists,
and needs to be changed.  It would be wrong to abandon lists purely because the
naming rules have an unexpectedly perverse effect.

	Cheers,
		Tony.
====
Anthony B. Coates
London Market Systems Limited
33 Throgmorton Street, London, EC2N 2BR 
http://www.londonmarketsystems.com/
mailto:abcoates@londonmarketsystems.com
Mobile/Cell: +44 (79) 0543 9026
[MDDL Editor (Market Data Definition Language), http://www.mddl.org/]
[FpML Arch WG Member (Financial Products Markup Language), http://www.fpml.org/]
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