Re: [ubl-dev] Invoice: Validating summary data

["G. Ken Holman" <gkholman@CraneSoftwrights.com>]

At 2009-05-22 15:44 +0200, Isak Hansen wrote:
>I've been tasked with maintaining a mediator-of-sorts for UBL
>invoices. We've been using it internally for a while, but are having
>issues after opening up for external systems which are sending us
>'broken' data. One example of this was an ignored-in-calculations
>invoice line containing the grand total for that invoice.
>
>We currently only validate documents against the schema, verify that a
>customer and supplier id is present, and that (supplier, invoice
>number) is unique. I know there's a lot of UBL-validation-tools out
>there, and wonder if any of these do sanity checks on the
>LegalMonetaryTotal and TaxTotal elements.

In mid-2007 I brought up in the committee that there was no published 
calculation model with which the HISC could interpret data input, 
such as would be needed in the implementation of an XForms interface.

I learned at that time that the UBL TC has not published any 
calculation models for the contents of a UBL document.  The UBL 
schemas are used to frame the information created by a user, but a 
user community is still responsible for determining the information 
that goes into the published document scaffolding.  Individuals 
within that community can then make sense of the fields of 
information that are exchanged.

Two important aspects of any calculation model are the handling of 
allowances and the handling of taxes.  It would not be under the UBL 
TC's purview to dictate how allowances and taxes should be handled by 
user communities, as each user community will have their own 
requirements in these areas.

The Danish OIOUBL project has published a calculation model for UBL 
documents used in Denmark, but I cannot quickly find a reference to 
it.  Perhaps if another reader on UBL-Dev knows the link to this, 
they can post it ... I'm confident I've seen it once as one of the 
OIOUBL documents (perhaps it was an OIOXML document).

>If not, what are the absolute minimum of fields we should be checking
>before accepting an invoice (for relaying), just as a guideline?

This will be based on your business needs.

>If someone could point me towards a resource for all the calculations I
>should be doing, that would be appreciated as well.

I think it will be up to you to publish the calculation model for 
your own community of users.  For those outside of your community, it 
becomes a specification document for those who want to do business with you.

The HISC work is in hiatus right now as we await new members to take 
a lead on the data input side.  Publishing a candidate exemplar of a 
calculation model is part of that work.  Then people who take UBL off 
the shelf can choose to use that calculation model or create their 
own, perhaps using the UBL exemplar as a starting point.

I would hope that we find a published document from the upcoming 
BII/PEPPOL work that describes a candidate calculation model the 
committee could use.

I would also be interested to see the formats by which people publish 
calculation models.  How modular are these?  Can different allowance 
and taxation models be "plugged in" to the calculation model as a whole?

This is an important area and nothing has been done on it in 
committee work since I raised the issue in 2007 as energies have been 
focused elsewhere.  Indeed I think this may have been overlooked in 
the writing of the customization document currently in public review 
as it would be important to a community customizing UBL to specify 
the calculation model they plan to use to populate their UBL 
instances.  I've just added this as a formal comment for the 
committee to consider.

Please consider submitting your work in this area to the UBL TC 
through the formal TC commenting mechanism (to cover off IPR issues; 
there is a button on the committee home page that takes one to the 
http://www.oasis-open.org/committees/comments/index.php?wg_abbrev=ubl 
page) so that the committee could consider publishing it as one of 
the candidate exemplars for users to choose from.  Please consider 
joining the HISC so as to undertake this as a formal activity of 
HISC, so that the subcommittee can be one step closer to implementing 
data entry demonstrations.

I hope this helps.

. . . . . . . . . . . . . Ken

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