== Geometric algebra question - involutions == 

 Might you know of "the" (or "a") geometric interpretations of the three main geometric algebra involutions (reversion, grade involution, and Clifford conjugation)?  I believe that grade involution corresponds to reflection through the origin, but I don't know about the other two. 

 ALSO, when representing a geometric algebra using a faithful matrix representation, where ordinary matrix multiplication corresponds to a geometric product, are there analogous matrix involutions to these geometric algebra involutions.  When using a sensible basis, the transpose is equal to the reverse, but I've found nothing for the other two. 

 Thanks.