Yes.
All information like that is laid out in section 2 just as you see it in Grannyviewer!
It's a solid block defined by the section index and it's pointer.
Section 3 has all the faces.
That's all those sections contain.
Section 1 contains all the information as to how to divide those into seperste meshes and the textures assignments.
Plus much more.
The default for sections in a GR2 file is 8.
Max sections is 32
(That info is from the Granny history at RAD Games)
Also from a RAD Games Blog?
Most GR2 files are not modified even though Granny allows modifications.
'The First Templar' is a GREAT example of a modified GR2 file!
Easy to read/write setup for the most part.