Picture identifiers

Pictures are flagged by means of an integer identifier (the picture identifier) which combines knowledge of a device name and a picture number in the same way that an SGS zone number does. Both AGI_ASSOC and AGI_OPEN return a picture identifier to the current picture on the given device. Pictures in the database can only be referenced by means of these identifiers which are returned to the application from the appropriate AGI routines. These identifiers should only be passed on to other AGI routines and should not be altered in any way by an application.

Once a picture is no longer required it is good practice to release it using AGI_ANNUL which liberates internal workspace. Picture identifiers can be automatically released by using a begin-end block (see this section).