The 
PCRF in Radiator has
                  been designed to be modular and uses a number of modules to process the
                  Diameter Gx and Rx messages, fetch and update information in the
                  
SPR, store Gx and Rx session information.
                  These modules are configured with separate clauses and referenced by their
                  identifier from 
<AuthBy DiaPCRF>
                  clause.
 
               A number of hooks are defined to customise the action when,
                  for example, usage monitoring thresholds are reached, quota runs out or
                  quota is used for the first time. The operators are encouraged to develop
                  their own functions and Perl modules to handle the different
                  events.