They done went and changed it agin, then:

http://tinyurl.com/2fksg7

faa-h-8083-13, pp101-102 (2003)

I expect that they WILL. The next update to the Practical Test Standard
will, no doubt, reference the Glider Flying Handbook for this maneuver.
The current PTS references the (otherwise excellent) Soaring Flight
Manual, unfortunately in this case.

The current PTS reads:

TASK E: BOXING THE WAKE

REFERENCE: Soaring Flight Manual

Objective. To determine that the applicant:

1. Exhibits knowledge of the elements to boxing the
wake (maneuvering around the wake).
2. Maneuvers the glider, while on tow, slightly outside the
towplane's wake in a rectangular, box-like pattern.
3. Maintains proper control and coordination.

Not exactly detailed, is it :-) ?