The Hand object represents a one-bone hand and a set of finger bones using guide objects to position and orient the bone joints. Two collections of guide objects are necessary to create a hand: a collection of finger guide objects to position finger joints; and a collection of "blade" objects that control the curl direction of the fingers. The finger chain is set up so that bone Z rotation is in the plane of the blade.
See CDK Object Reference for complete list of objects available in the Character Development Kit.