auto incrementing digit pool

["mike@grounded.net" <mike@grounded.net>]

Is there a way of creating an attribute which can be assigned a value which auto increments using an external file.
In other words, say I use the employeeNumber attribute but I want the value to be entered by picking the next value from a file.

In my file, I might have

000123
000124
000125
000126
000127

Then when I run an ldap connection from my remote application, it would pick the next number if it doesn't exist on any account.
The next problem is I don't know how ldap works in terms of keeping track of things.

When I sync my application database with ldap, does it, or can it, check all of the users to see if a value is assigned or is that beyond it's functions? Or, would keeping track of the values be something which needs to be done on the application side? The programmers tell me that there is no means of going back to ldap to identify if a user has been assigned a value, therefore, assign the next.