WORK IN PROGRESS PLEASE IGNORE FOR A WHILE
This page will describe how EMAN2 defines the asymmetric unit, and its associated mirror portion, for each of the symmetries. This is mostly important in the context the the projection tools (EMAN1: project3d, EMAN2: e2project3d.py) which project quasi-uniformly over the asymmetric unit for each of the symmetries, generating the reference images for particle classification.
The asymmetric unit of a symmetric 3D object can be defined in many ways. In one regard, it is the 3D subvolume of the entire 3D object that an asymmetric object can exist inside of In EMAN1 it was imperative that the mirror portion