In debug GET_ASSIGNMENTS (CL_HRESS_AS_PERNR_SELECTION)
CALL FUNCTION 'HRXSSCE_GET_PERNR_GRP_INFO'
EXPORTING
appl_path = ''
appl_name = iv_application_name
servicekey = lv_service_key
user = sy-uname
molga = iv_country_filter
IMPORTING
pernr_grp_info = et_assignment
group_title = ev_group_title
messages = et_message.
It uses sy-uname if PERNR_MEM_ID is npt assigned.
PERNR_MEM_ID is used in various application because of security. There is no value of pernr in the URL only MEM ID. In other case experienced user can change pernr in URL parameter and see restricted data!