Rect (rectangle texture definitions)

HI , I am making a theme and would like to know where I may find the definitions of the rect and how they are defined .. such as left, top, topleft ,middle rect and so on for the textures..

Thanks ..

Checkout the Developer Guide; https://www.fantasygrounds.com/wiki/...eveloper_Guide

Specifically the framedef tag portion (I think); https://www.fantasygrounds.com/wiki/..._Assets#Frames

nine slices!
tip: they are not all required...