Use of Functions

[PhilOfPerth]

Guys, I don't know why you like to overthink these things.   Let me give you some simple truths about SUBS and FUNCTIONS:

1) SUBS and FUNCTIONS perform in exactly the same way.  Anything you do with one, you can do with the other.  The *ONLY* difference is that a FUNCTION returns a value via the NAME, while a SUB doesn't.  There is absolutely nothing stopping you from swapping between a SUB or FUNCTION interchangably.

The only caveat to that is that FUNCTIONS can be passed as parameters or operators and SUBS can't.  A SUB has to be a stand-alone process and can't be part of the same line segment or passed as a parameter or operator.

X = X + Foo(whatever)   <-- Foo is a Function, it can be used in the formula to the left with no issue.
FUNCTION Foo (whatever)
   Foo = whatever * whatever
END FUNCTION

You can't do something like:

X = X + Foo whatever, return   <-- Trying to call this sub will generate errors and die on you.  
SUB Foo (whatever, return)
   return = whatever * whatever
END SUB

Foo whatever, return: X = X + return  <-- Note that this *WILL* work just fine for you.
SUB Foo (whatever, return)
   return = whatever * whatever
END SUB

There's honestly no real magic difference between one or the other.  The only real difference is that FUNCTIONS return a value from their name, and they can be used as a parameter or operator.  That's it.  Otherwise, the two follow 100% of the same rules and behavior with each other.

Ok, thanks both. I guess I'll stay with the "devil I know" (a bit), then, rather than the devil I barely knew at all until this thread. 
At least, I know what the devil looks like now!
Much appreciated.