Sewing pattern base type thing?

I was reading a book called 'How to use, adapt, and design sewing patterns' by Lee Hollahan a while ago, and i returned it to the library without writing down something i wanted to remember... It talked a bit about patterns that are sold that can be used to make your own patterns. So basically, you would use them as a base. It gave pattern numbers and everything but i completely forget what that *type* of pattern was called... does anyone know what there called or anything? thanks!