In macros you assign the variables when you call the program. Sinha mentioned them when he spoke of sending 'arguments' to the macro. In this macro we need #4 and #5. These are recognized by the control as I and J, respectively. So when you call the macro, use the syntax :
From main program or MDI screen :
G65 P8200 I(whatever value you wish to assign #4). J(#5).;
for example - G65 P8200 I101. J199.; would assign 101 to #4 and 199 to #5, and the macro would start it's loop.