Up to V2R1, the AS/400 could only vary off a display device after so many invalid sign-on attempts. This is fine in most cases, but it can be dangerous. For example, suppose you just ended all subsystems. Your AS/400 is in a restricted state (another way of saying, it's dedicated).
In a restricted state, only the system console remains active. If you sign off (or the system times out your job), you must sign on again. Now you make a mistake and enter the wrong password repeatedly--causing the system to vary off the console. No display stations remain active; you have to IPL from the control panel to regain control. Not an attractive thought, is it?
System value QMAXSIGN has always controlled how many invalid sign-on attempts are allowed or, actually, upon which invalid sign-on attempt the system will vary off the offending display station.
Now there's system value QMAXSGNACN (maximum sign-on action), which can have three different values:
'1' system will vary off the display station, as it was before V2R1.
'2' system will disable the user profile.
'3' system will vary off the display station and disable the user profile.
Disabling user profiles is a new feature of V2R1. When a user profile is disabled, the user cannot sign on even if supplying the correct profile name and password. The user profile can be disabled either automatically (as a result of several invalid sign-on attempts) or manually (with the CHGUSRPRF command). The user profile remains disabled until another user runs CHGUSRPRF to change it from STATUS(*DISABLED) to STATUS(*ENABLED).