Ok, but I do not manage to get your example
/********* Begin Procedure Script ************/
BEGIN
mytab = select user_name from users;
var_out = apply_filter(:mytab, :userNameFilter);
END
/********* End Procedure Script ************/
running with the apply_filter syntax and with input parameter userNameFilter and value blank (i.e. '').
The placeholder variant might work, but then
1) we have a variable and hence the corresponding attribute has to be part of the output of the CV in order that the variable can be created,
2) the source ("_SYS_BIC"."LBPB/SCV_USERS" in your example) has to be a HANA view and cannot be a table or a database view.
Regards,
Ingo