QA Build provides all the facilities needed to control access to a system, through the use of logons, passwords and a menu. A menu can be designed to provide options to call other procedures, as described in the section on Menus and Function Keys, and also to make use of the facilities to control access to the system using DP4 usernames and passwords, to call other QA Build programs and call non QA Build programs. If you wish you can completely bypass menus built using DP4 Menu Pages. QAB menus offer more flexibility than ones built for DP4 itself. The only disadvantage is that there is less memory for running other programs, though this is unlikely to be a consideration except on very old systems or perhaps hand-held devices.
The facility to call other QA Build programs is also useful in splitting up a QA Build application which would be too large or cumbersome to exist as one program. For further information on handling large programs see Overlays.
The Program and Special Command facilities are all accessed through the use of procedure bodies of type Run another program.
The Special Command facilities include user log-on and log-off, and facilities to change passwords and per-user preferences such as colour schemes or language. There are also some facilities that are not specifically related to users.