I'm building a relatively simple form that a customer will use for
sales reports. This form is hosted using Forms Services in MOSS  -
each salesman (about 50-100 persons) will have his own site with a
form library. Each library uses a centrally managed Site Content Type
(with fields published as columns) and each site is created from a
template.

I have a field called 'Report Number'- in this field I want to
generate, *on opening the form*, a unique ID number based on the user
ID (windows login account name) and a consecutive number based on the
forms existing in the library - eg: 'jonhil-12345'. The user ID I have
already retrieved to populate another field so I can reuse that or use
the defualt 'userName()' function.

The question is - how do I create the automatic number sequence - to
start at 1 and increment within the existing library ??

(Note: the specific library cannot be referenced since this form
template is a centrally managed Site Content Type and all the
libraries will be set to use this - no forms are published directly to
a library)