You can retrieve application server file names in the F4 help function by submitting program rs_get_f4_dir_from_applserv.
SELECTION-SCREEN BEGIN OF BLOCK 002 WITH FRAME TITLE text-002. PARAMETERS : p_aps LIKE rlgrap-filename MODIF ID pth . SELECTION-SCREEN END OF BLOCK 002. DATA : path_name(150) TYPE c. AT SELECTION-SCREEN ON VALUE-REQUEST FOR p_aps. SUBMIT rs_get_f4_dir_from_applserv AND RETURN. IMPORT path_name FROM MEMORY ID 'PATH_NAME_SDL'. p_aps = path_name.