I'm wondering to what extent is Mumford's Geometric Invariant Theory treated in the SGA volumes, and what's the Grothendieck point of view of GIT.
I looked at the TeXified and annotated version of SGA3 and found some reference to Mumford's GIT book in the modern annotation, especially in Exposé 5, quotient by groupoid. I think GIT is one of the major advances in Algebraic Geometry in Grothendieck's time, if the answer to my question is yes, then how (it is treated)? And if the answer to my question is no, then why (it is not treated)?
Also, has anyone seen Grothendieck's comments to GIT appeared somewhere?