When adding project parameters to an element, we should be able to enter a formula that references other parameters. For example, we wanted to add part numbers to our mullions (which are based on the length of the part). It should have been as easy as entering a formula in the new part number parameter like you would for any other family, but I got an error saying "Formulas cannot refer to other parameters." Now we either need to accomplish this via an updater with the api or create a complex family to mimic the functionality of a curtain wall.
