Using option "18=Input parameters" with a User-defined function on the "Work with User-defined function" panel displays the list of all Input parameters of the User-defined function on the "Work with Input parameters" panel. After the User-defined function is created this list is initially empty. The Input parameters of a User-defined function are input parameters (preceded by the two input parameters for ITP internal use) of the program execute function registered with the User-defined function.
On the "Work with Input parameters" panel the Input parameters of the User-defined function can be manipulated: