How to use this Formula,"Formula That Returns Strings"?

[mike99]

I got this in the wikihelp, "Formula That Returns Strings","IF (Length < 900, “Opening too narrow”, “Opening OK”)"

but how to use it?
Is that the string will pop up like a message box?

[irneb]

You use it as the formula in something like a parameter. E.g here's a sample of a door family's parameters using formulas:
88690
You use that IF function when the parameter you place the forumla into is a text parameter. E.g. say you'd want to indicate in the Door's param what type of lintel is used depending on the width of the door. So here I add a Text Parameter
88691
And then adding even nested if's to show more options:
88692

[mike99]

thanks, I'll try it again

[mike99]

I got this, thanks a lot

[irneb]

Pleasure. Glad to help.