unique values

["A. Schulze" <sca@andreasschulze.de>]

Hello,

while planning a data scheme update we found it handy to have a unique  
value for each entry.
short time later we found "entryUUID" :-)
But we are still unsure.Should we simply use entryUUID or should we  
extend our schema
to hold a new attribute similar to entryUUID.

so what are the pros and cons on using entryUUID for a second purpose?

  + entryUUID is implicit available for each and every entry
  + automatically generated
  + saved as part of our backup using slapcat

  - what happen on a complete disaster restore?
    will the entryUUID values remain if we build a new server from a  
slapcat backup?

  - a separate but similar attribute has to be defined
    is there a suggested schema? "grep -ri uuid  
/path/to/openldap-source/servers/slapd/schema/"
    did not disclose the definition of entryUUID. It's somehow  
defined in servers/slapd/schema_prep.c

  - a separate but similar attribute has to be written while creating  
a new entry
    could that be automated somehow?

  - what is 'NO-USER-MODIFICATION' in a schema definition and what  
are the implications
    if I define an attribute as NO-USER-MODIFICATION?

Do you have any thoughts or suggestions on this?
A quick search in the list-archive didn't helped me to answer my questions.

Thanks,
Andreas