Thanks for the reply. Perhaps I was confused by the statement in the "Help" entry under "Formulas": "Functions - make use of your functions in your formula." Is "your functions" a typo? I would otherwise lead me to believe that I can create a function from a calculation. The advantages would be quicker and less error-prone writing of complicated calculations, the ability to write and debug fragments of a calculation and to modify them separately, and the shortening of what might become quite long individual calculations.
User functions wouldn't require global variables, but they would need argument passing (which you already must have), and some ability to stack function calls.
I hope you can introduce this capability some day (but then, everyone's an architect, aren't they).