Dialog Processor and List processor

A screen sequence is handled by dialog processor.
Within a screen, list sequence is handled by list processor.

The dialog processor handles flow logic screen after screen , triggering the appropriate
ABAP modules in the module pool pgm.
One can switch between dialog processor and list processor using
leave to listprocessing , call screen commands.


The o/p of report pgm is called list.
Conceptually , the o/p comprises of a list screen.
The list screen in turn comprises of basic list+details lists.
Each of these lists is assigned a list index starting from 0 for the basic list.
The index of a particular list can be retrieved from sy-lsind system field.
The list processor handles 'at line selection' and 'at user command events'.

At the end of displaying the list , the list processor checks if the sy-lsind value is lesser than the
current list index. If so , the lists in between are deleted , the current list is set to the
number in sy-lsind.

Suppose you want to move from 3rd list to 1st list using back button ,
just decrement the sy-lsind value programatically and then press back button.