[ver] (AW/Fwd) to consider before call

----- Original Message ----- 

From: A. G. 

To: Stephen Green 

Sent: Tuesday, April 12, 2005 1:47 PM

Subject: Re: [ver] Anything to consider before call?

Stephen:

 

Many thanks.

 

Yes, I think I actually figured out a solution, although i haven't had time 
to really work up the samples yet.

 

Substitution groups.

 

I was looking at your samples, and I realized that the one thing we do 
differently in the SDMX implementation of this aspect of NDR (we don't use all 
the rules, as they don't always apply) is that we have each extendable type 
represented as the head of a substitution group. 

 

Thus:

 

In NS A v. 1.0, I declare Item and Line. Each type is the head of a 
substitution group.

 

In NS B v 1.0, I declare the Invoice, as per your example from our earlier 
call.

 

If I go to create v. 1.1 of these namespaces, I can extend the Item in 
NS A v. 1.1, and also extend the Line (which contains the Item). If I indicate 
that the Item is a member of the Item substitution group, however, then I get 
the extended version of Item instead of the old one when I create the new Line 
(which, of course, I use in the new Invoice, which can also be extended).

 

Had you considered this approach? It has some ramifications, but avoiding 
the problem you ran into is exactly why substitution groups were 
invented. I know this was discussed in NDR soime time ago, but it clearly 
didn't make it into the spec.

 

I thionk we should discuss this on the call, unless jet-lag is making me 
miss some obvious flaw.

 

Cheers,

 

Arofan

Stephen Green 
<> wrote:

  
  

  
Arofan

  
 

  
I just realised you can't post to the ubl 
  list.

  
If you've anything you'd like be posted to the 
  list

  
before the meeting today, feel free to post 
  it

  
to me and I'll forward it on. However I'll be 
  away

  
from email for 1 hour prior to the 
  call.

  
 

  
Unfortunately I'll be out of email range 
  Thurs

  
and Friday but we can sort something out 
  before

  
then. (The modeling team have had to send 
  me

  
to a meeting in Europe so I'll only have 
  limited

  
contact Thursday and Friday I'm 
  afraid.)

  
 

  
All the best

  
 

  
Steve