In many cases, it is convenient to predefine a set of session parameters that could be sent in the BIND. When a set is defined, a name is associated with the set. That name is known as the logon mode name. The logon mode name is used in Initiate requests, and in the LOGMODE operand of certain macroinstructions and VTAM® operator commands to identify the set of session parameters.

Additionally, in VTAM, a logon mode name implies a particular class of service used for the session. Class of service is a set of characteristics used to construct a route between session partners.

Several session parameter sets, each with its own logon mode name, can group into a table known as a logon mode table. There is a logon mode table, a default logon mode name, and an associated default set of session parameters associated with each LU that can act as the secondary end of a session,

Instead of using a predefined session parameter set, an application program can build a set of parameters at the time it is needed. The set of parameters is built in an area of the application program known as a BIND area, whose address is placed in the NIB used for the OPNDST or OPNSEC macroinstructions.

Refer to the z/OS Communications Server: SNA Network Implementation Guide for information about logon mode tables, class of service, and other aspects of the session parameter definition process.