Introduction

z/OS issues messages from JES2 to different locations in the following ways:

Through the WTO and WTOR macros to operator consoles, the hard-copy log, a SYSOUT data set, or the job log for the job's system output message class. Routing codes determine where (such as the system log (SYSLOG)) the messages are to be displayed or printed.
Message routing codes provide the ability to route system operator messages to the locations where they are needed. The routing codes indicate the functional areas to which a message is to be sent. More than one routing code may be assigned to a message to send it to more than one console.

Message descriptor codes identify the type of message being written so that individual console support may determine how to handle the message. Specifically, this type of code determines how the system will display and delete the message.
Through the WTL macro or the operator LOG command to the system log (SYSLOG).
Through the access methods directly to an output data set or a display terminal.