"I have calculation that returns a list of values from a related field"
I suppose that your calculation is something like: List ( YourTable::YourField )
If so, you'll need:
1) to define a new calculation field in YourTable with calc: Left ( YourField ; 3 )
2) to change your list calculation to List ( YourTable::YourNEWField )
Thanks, Ray. I was thinking I could do it in one calculation, but of course your solution makes much more sense.
It probably IS possible to do in a single calculation, but that would be with ExecuteSQL() and the SQL version of Left instead of using the list function. (This requires Filemaker 12 or newer to do.)
Sorry PhilModJunk... have to speak up here. I don't see anything in the original post that mentions SQL. It was a simple question and a simple calculation was the answer.