Did you try to find it into "Library item parameter" instead of "Add fields" ?
You are able to find others parameters like this...
Christophe - FRANCE
Archicad Designer and Teacher
Archicad 15 to 26 FRA FULL
OS 11.6 Big Sur - MacBook Pro 2015 - 16Go RAM"Quality is never an accident ; it's always the result of an intelligent effort" John Ruskin