This is more of a standards question than a how-to question. Can I assume that texture compression and byte sized vertices are supported by all OpenGL ES implementations?
I'm a little confused by the different types of extension flavours (ARB/EXT/ES specific / Core). I'd appretiate some clarification as I'm working on mobile devices that would really benefit from textures compression / byte verts to save memory. It would be nice if I could assume they have both features.