It is possible that you can find some suggestions in

Bollmann W, Crystal defect and crystalline interface,- Springer, Berlin, 1970

Bollmann W, Phil.Mag. 16, 363, 383 (1967)

where DSC lattice method is introdused for GB dislocation lattice construction.

You can find later papers of other authors, where this theory is developed.

I can also recomend you

A.N. Orlov, V.N. Perevezentsev, V.V. Rybin. Grain Boundaries in Metals. - Metallurgiya, Moscow, 1980 (In Russia)

Regards

Sergei Prokofjev

Well, it is the general procedure to find  misorientation (where the orientation relationship (OR) has smallest deviation from the CSL OR) among several equivalent description. 

Your question may be related to why we need to find the smallest deviation (angle)?

Because this kind  of deviation has physical meaning. For example, as we know the dislocation spacing  D for symmetry tilted grain boundary is equal to D = b/theta, where b is the Burgers vector and theta is the rotation angle (deviation angle). As you can see different theta means different dislocation spacing, so we need to select smallest theta which corresponding largest dislocation spacing (low energy), and this dislocation has physical meaning. For the details, you may refer to Ballman's O-lattice theory (mentioned in the last post by Sergei Prokofjev). BTW, there is simple way to find the misorientation in his book.

By applying all of the symmetry operators you are applying 24*24 symmetry equivalent operations. Switching symmetry accounts for the opposite route of rotation from axis set 1 into set 2 and vise versa. So you end up with 24*24*2. When doing this for a reference system, you are basically finding the disorientation between your axis and the perfect reference. In other words you are finding the disorientation axis that rotates your given orientation into the perfect reference. This is known as the mis-misorientation. You are only concerned with the angle because the axis doesn't really have any physical meaning. Your axis needs to lie in the fundamental zone in order to be the disorientation (minimum misorientation). Ob and Oa are the list of symmetry operators (matrices) while ga and gb represent direction cosine matrices which describe rotation to and from each set of axis.