Spec Sheets > Allow or adding custom columns to specs

Within configuration settings, have an opportunity to add fields for certain spec sheets. For example, in my tile selections, I like to include a field for Grout Color. In my lighting spec sheets I like to include a field for Bulb Type, and # of Bulbs… things like that.
I like that I can hide and reveal the current fields, but I wish I could further customize the sheets to have the fields I prefer. Thank you!