There are four types of cal : Named/Doc/Session and Usage Cal.
Name cal is based on the identity of a person, which we can run on a machine for a specific user.
While the concurrent cal ( *Session cal) identification of user is not necessary, In this the number of session from one user on a machine is allowed.
Mainly we have 3 type of cal.
1) Named Cal
2) Document Cal
3) Session or Concurrent Cal
1 Named Cal : Full Access
Multiple developer work simultaniously
Work on multiple qvw.
2) seesion Cal: Any user view desktop for short period of time.
Can see all Thumbnails
Small Business Edition heaving Named Cal license only
Enterprise Edition heaving all 3 type license