The occasional user who has a single repetitive graphic problem which is part of another complex program. Interactive control is not wanted. This is very efficient and flexible. A programmer wanting to solve a single repetitive graphic problem for use by other people. Interactive action is not wanted.
Simple programming is of little importance, but efficiency is a major problem.
A programmer wishing to integrate elaborate and flexible graphic applications as part of a more complete data analysis system. Interactive control by the user and error recovery are necessary. Special entries are used to process possible options. The advantage of this mode is to provide a more standard program interface. Not all commands will be accessible in that way, and it is marginally slower than the previous mode.