You can group routes based on characteristics such as security, transmission priority, and bandwidth of the routes. The characteristics of a particular group determine a Class of Service (CoS). VTAM® provides classes of service for subarea and APPN routing.
See Subarea class-of-service table for information on the macroinstructions that define a subarea CoS table and APPN Class of Service definitions for information on the statements that define an APPN CoS. See z/OS Communications Server: SNA Network Implementation Guide for a discussion about how classes of service are used.