Problem with document consistency

[Peter Larsen Borresen <plb@itst.dk>]

Dear subcommitee

One major problem with splitting information into more documents is that how
can you know whether the document that is refered to is still there? In UBL
there are refered to two kinds of documents. Procument documents that are
defined by UBL and external documents. When it comes to the procurement
documents they are must often stored in the same ERP system. For external
documents (contracts etc.) the saftest way to maintain them is to embed them
in the procurement document. That is what we have done until now in Denmark.
Many of our invoices contains TIFF documents of other specifications.
However I am of the opinion that embeddding is not the way forward since it
results in huge documents and a diluted document definition. What is for
instance an invoice with a contract and a requisition form? How much can you
put in an invoice and still call it an invoice? 

This leaves med with the conclusion that even that we do not want to solve
the problem with maintaining two documents consistense, we need to adress
problem. My proposal is therefore that we add t one ASBIE and a BBIE to
documentReference:

GuaranteeStoragePeriode [0..1]: PeriodeType    The periode when the document
is guaranteed to be hold persistent on the storage.
HashCode [0..1]: Text                                      A code use to
verify whether there has been tapered with the document since it was stored.

With these two elements it should be posible to handle external stored
documents almost as good as if they where stored internally.

Best regards

Peter L. Borresen