"AT-STs will no longer be deployed on planets with an abundance of trees or other known obstacles such as rock-wielding primitives."
―Imperial AT-ST Manual, updated shortly after the Battle of Endor[src]

The Imperial AT-ST manual was a manual written by the Galactic Empire to guide the reader on the aspects of an Imperial AT-ST.

It was updated sometime after 4 ABY, to inform that AT-STs would no longer be used on planets such as Endor, alluding to the fact that many AT-STs were destroyed because of dangers on Endor.