Hi!
I don’t know if I understand you correctly, but maybe what you need is setting the parameter value before the macro call. You can do that in the parameter script with the PARAMETERS command. I see 1200/900 setting depends on Element_type parameter of your object, use GLOB_MODPAR_NAME global variable to check whether last parameter modified was "Element_type", and if its new value is 2, set parameters B = 0.9. Then you can call your macro in the 2D script using PARAMETERS ALL, the B parameter will be 0.9.
Péter Baksa
Library Platform, Software Engineer
GRAPHISOFT SE