The cn=schema entry has a multivalued attribute, attributeTypes, that contains definitions of each attribute type in the directory schema. You can read those definitions by using the ldapsearch(1) command.
You can use DSCC to perform this task. For information, see Directory Service Control Center Interface and the DSCC online help.
Use the ldapsearch command to view all the attribute type definitions that currently exist in your directory schema.
The following command displays definitions for all attribute types:
$ ldapsearch -T -b cn=schema "(objectclass=*)" attributeTypes
The -T option prevents the ldapsearch command from folding LDIF lines, so you can more easily work with the output using commands such as grep or sed. If you then pipe the output of this command through the grep command, you can view only the user-defined extensions to directory schema. For example:
$ ldapsearch -T -b cn=schema "(objectclass=*)" attributeTypes | grep "user defined" attributeTypes: ( 126.96.36.199.5.6.7 NAME ( 'blog' 'blogURL' ) DESC 'URL to a personal weblog' SYNTAX 188.8.131.52.4.1.14184.108.40.206.15 SINGLE-VALUE X-ORIGIN 'user defined' )