CAL is nothing but an CLIENT ACCESS LICENSE.
To connect to a QlikView Server (QVS), each client needs a Client Access License (CAL). The CALs are purchased with QlikView Server and tied to the server serial number.
A Document CAL is assigned to a unique and identified user who may access only the one QlikView document to which the Document CAL is assigned.
Multiple Document CALs can be assigned to a particular user.
For example, if a user connects to two QlikView documents, the user will have been assigned two Document CALs.