A lock mechanism enabling locking of a bi-parting set of right hand and left hand door panels respectively suspended from a right hand and left hand door operators, to be driven by the door operators for covering and uncovering an aperture disposed within a passenger transit vehicle. The method is based on the variation of the plasma parameters to provide a well-controlled anisotropic etch, while achieving a very high etch rate, and a high selectivity with respect to a mask. The boat propulsion system achieves both the acceleration performance and the maximum speed desired by a user. The apparatus may determine the paging resources on which to listen based on information received in peer discovery signals received from other wireless devices.