Identifying source of ldap entries

Hello,

We have a central ldap server, many application save their contacts there.

So, my question is that, is there common way where we can save origin of the contact (which describe from where the contact's data come) ?

e.g we have three application(crm, ...): a1,a2,a3
and the contacts will have attrib. which will store: a1 or a2 ... etc

Is there any well known way or practice ?

Thanks in advance.

If could save this info, it makes easy the syncronizations in the future.