NUM_ARGS( )
The NUM_ARGS( ) function returns the number of command-line arguments with
which the current 4GL program is invoked.
The NUM_ARGS( ) function returns an integer, corresponding to the number of
command-line arguments that followed the name of your 4GL program when the user
invoked it.
You can use the ARG_VAL( ) built-in function to retrieve individual arguments.
By using NUM_ARGS( ) in conjunction with the ARG_VAL( ) function, the program
can pass command line arguments to the MAIN statement, or to whatever program
block invokes the NUM_ARGS( ) and ARG_VAL( ) functions.
Reference
ARG_VAL( )