One of the things that is very frustrating when using formulas in Revit is that you can’t make the result text.
If you have ‘Length’ and ‘Parameter A’ and you want the result of ‘Parameter A’ to be ‘TRUE’ if the Length is smaller than 1200mm and ‘FALSE’ if the Length is greater than 1200mm.
For this you would think the formula should be…..
Parameter A = if(Length < 1200, ”TRUE”, ”FALSE”)
But alas, you will be greeted with this error message…..
What Revit is telling you is that you cannot have the result of a formula being text…… :(
So in order for this to work we need to trick Revit by creating 2 additional dummy parameters, TRUE and FALSE, with their values being TRUE and FALSE respectively.
Now you can create your formula and all you have to do is leave out the apostrophe marks…… :)