Addressing is based on Logical Service Access Point Selectors (LSAP-SELs), numbered from 1 through 127. Because of the small range of values available, it is usually better not to bind sockets directly to an LSAP-SEL. Instead, the Information Access Service (IAS) provides a means for dynamic binding of sockets to LSAP-SELs.
To use IAS, a server application binds a socket to an IAS service name. The client application uses the service name when using the connect function. Neither application must be notified of the LSAP-SEL assigned by the IAS.