From parallel waves: Two on one end of one wave do a box circulate with the two on the opposite end of the other wave. Ordinarily it is done from a wave that has men on one end and girls on the other end of the waves and the call is either Men Diagonal Circulate or Girls Diagonal Circulate. Finishes in parallel waves.
Buford Evans 1971
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.