This is a standard event for form GUIBBs, that is triggered from a button on the screen. The name of this button can be freely defined in your application, and the way your code reacts to the event is also up to you. So this is basically a very generic event that can be reused by many applications.
Example
Code example for standard event for forms:
Syntax
CASE iv_eventid->mv_event_id.
WHEN gc_event_display.
* 1. code to run your report/call function module etc,
* that generates e.g pdf.
CALL METHOD me->produce_form
IMPORTING
ev_pdf_content = lv_output_content
et_messages = et_messages
CHANGING
cs_screen_parameters = <ls_screen_parameters>.
* 2 .code to put e.g. pdf into the document container:
mo_document_container->set_document(
iv_content = lv_output_content
iv_content_type = cl_hrgrt_document_container=>gc_doc_type-pdf
iv_header_text = lv_header_text ).
ENDCASE.