When NetMaster initializes, the AOM SSI command prefix default character is set with question mark character=?. This, in turn, can cause a conflict with other regions, such as IBM's DB2, even if NetMaster has ? as AOM SSI command prefix for a few seconds, until it is changed on startup processing of /PARMS group $RM OPSYSIDS parm AOM SSI Command Prefix String.
To make sure the AOM SSI command prefix default character ? is changed at early initialization, follow these steps: