[trebleshot]

One of these days I'll get around to finishing that section in the reference guide. T-crotches are indeed ones that have a pelvis that forms a "T" due to the hip joints (and sometimes the waist joint) being swivels and the hip joints are cut perpendicular to the waist. The majority of Amazing Spider-Man 3.75" figures had this kind of crotch, as did most of Star Wars (until recently) and the Green Lantern 3.75" line.

V-crotch is pretty much the same thing, only the cuts for the hip swivels are set at a 45 degree angle to the waist, forming a "V". Usually you only see this with female figures, for some reason.

Based on that, I would have to assume that "H-crotch" is referring to the DCUC-specific hip design (which officially is a variant of a ball joint, only most of it is hidden inside the pelvis area).

Rocker ankles are where the figure has a second joint that connect the foot to the ankle at an angle to the actual ankle joint, allowing the foot to swing or "rock" from side to side in relation to the ankle/leg. This allows the figure to stand in a more natural/relaxed position with the legs angled out but the feet flat on the ground. Figures without rocker ankles either stand in the military-style "Attention!" pose if their feet are flat or one or both of the feet are angled off the ground slightly.

...I hope that makes sense.