Even with a document level script you would need to call it in every calculated field.
I you were to write "app.alert("Hello World");" as a document level function, it would only execute when the PDF was initialized or opened and not again as long as the PDF remained open.
If you rote a document level function using JavaScript like:
function Hello() {
appp.alert"Hello World, I am a function");
return true;
}
It would never run until called with a JavaScript statement like "Hello();"
So even with a document level script and preferably a function, you still would need to edit every calculation to call the function or the script would never run.
You could also create a document level function to suppress the zero display and then write more code to add the call to this function to the calculated fields.
You need to learn more about the scope of items, how events are processed within a PDF, what functions are and how to use them effectively. You might want to start with getting or linking to a copy the Acrobat JS API Reference.
