ABAP Keyword Documentation →  ABAP Glossary → 

dynpro flow logic

Procedural part of a dynpro with its own programming language, similar to ABAP. Is executed in the application layer. Is separated into the processing blocks PROCESS AFTER INPUT, PROCESS BEFORE OUTPUT, PROCESS ON  HELP-REQUEST, and PROCESS ON VALUE-REQUEST, which react to the dynpro events PAI, PBO, POH, and POV and to the dialog modules of the associated ABAP program.

More