Abstract: Two parts (120, 160) can be mated and secured from relative movement in three different orthogonal directions or planes by the use of a novel, two piece, plastic fastener structure. The snap fastener has an integral interlocking tab (170) that serves to constrain the movement in a third direction or plane. The snap fastener additionally consists of an operative component (110) and a securing component (150). The operative component has a resilient member (112) that deforms to receive a catch member (152) on the securing component when the operative component and the securing component are snapped or mated together. One of the two components contains an opening (180), while the other contains a body portion shaped more or less like a tab or tongue which is capable of being inserted within the opening when the two components are mated. When so inserted, the relative movement of the two components is restricted in three directions, without the use of a remotely located securing means.