Hi Mark

Apologies for the tardy response to your email.

First - I think we need a new name.  Tracking id has a specific meaning in CMIP5
land and I can already see scope for confusion ;-).

I can't really define a proper use case because I don't really understand the
lifecycle of global ids in the portal.  However . .  .

I want to generate a set of CIM documents covering a project, a model, N
simulations, and N data objects.  If I create and complete them in order - project
-> model -> simulation(s) -> data object(s), I should be able to find the relevant
referencing information in my database.  But the problem is that I don't store CIM
documents I generate them on the fly from our metadata database.  So I create the
top document in the reference hierarchy and give it a local id; I then have to store
this id temporarily while I create the other documents; again giving them local ids.
 These local ids can be used to regenerate the CIM documents from the database
whenever required (mako_templates).

So far so good.  If I send these documents to a collaborator for their own use, no
problem.  However if I send them to the portal I understand that the local ids are
going to be changed/extended to a global id.  But I don't want to maintain these
global ids in my local system and thus couple the portal and my local system
(security restrictions on my site).  So how do I exchange multiple versions of a
document with the portal and our metadata repository.  I envisage an id tracking
service would provide a transformation between a local id environment and the global
id environment.  At the moment I am flexible how I define the local ids, but this
will need to change in the next couple of months, so it is an opportune time to
resolve this.

Not a very good description - probably because I don't really understand the metafor
id model.

Mark