uniqueIdentifier, pilotObject, cosign.schema

[ms419@freezone.co.uk]

I'm trying to create LDAP entries with "uniqueIdentifiers". I thought I 
could simple add "objectClass: pilotObject" to these entries, but it 
turns out "pilotObject" is commented out of "cosign.schema".

Why is "pilotObject" commented out of "cosign.schema"? Can I simply 
uncomment it? Can someone recommend an alternative attribute to 
"uniqueIdentifier"?

Thanks!

Jack