More

It may be desirable for an application to store information in the database that is outside the scope of the routines provided. For this reason an application can access a MORE structure using the routine AGI_MORE and save arbitrary HDS objects within it. A MORE structure can be created for each of the pictures in the database. It must be stressed that if an application uses this facility then it is responsible for the contents and whatever any subsequent application may make of them. Also an application may need to cope with the situation of a corrupted structure.

The MORE structure is accessed for reading and writing using the routine AGI_MORE

          CALL AGI_MORE( PICID, ACMODE, MORLOC, STATUS )

The access mode (ACMODE) controls the action of this routine. If the mode is 'WRITE' then an HDS locator to an empty MORE structure is returned. If there was no previous MORE structure then one is created, and if there was a structure present then the previous contents are erased. At present there is no lock to prevent one application erasing a MORE structure being accessed by another. If the access mode is 'READ' or 'UPDATE' then the routine returns a locator to the top of the MORE structure, unless there was no structure present in which case an error is returned. The HDS locator returned by this routine has to be annulled by the calling application.

The presence of a MORE structure can be tested using the routine AGI_IMORE. The return argument is true if a MORE structure exists for the given picture, otherwise the argument is false.