Security Management - Oracle 10g/11g Data and Database Management Utilities - page 261

Shared schema
Once the database has been registered, you can create a schema that can be shared
among the Enterprise Users.
Connected as SYSDBA a user named GUEST is created. This user is different from a
regular user, as this user is not authenticated at the database level but at the SSO
level. When a user is created using the IDENTIFIED GLOBALLY clause, the user is
authenticated in the LDAP.
Once the user has been created it is granted privileges, just like any regular user,
with the GRANT command.
$ sqlplus / as sysdba
SQL> create user GUEST identified globally;
SQL> grant CREATE SESSION to GUEST;