Hi,
You can write it like that and it will compile but it won't work the way you want it to.

The program starts from the beginning and executes one instruction at the time.
* Turns on the LED
* Waits 500ms
* Turns off the LED
* Waits 500ms
* Jump to Loop1 and starts over.

The program will act as if the Loop2 and Loop3 routines wasn't even there.

And again, make a habit of writing your defines in UPPER CASE otherwise they'll have no effect.
Code:
define OSC 4     ' <----- OSC must be uppercase or it will not have the desired effect!
/Henrik.