A single crystal silicon etching method includes providing a single crystal silicon substrate having at least one trench therein. The conductor film is constructed of a cylindrical portion and two flat portions, and is formed by subjecting the surface of the dielectric to metallization or the like. A first time stamp is prepended to the transport packets when the packets are received from the headend. The method comprises the steps of. Implantable devices incorporating operational circuitry for performing such methods are also included in other illustrative embodiments. The wheelchair is walked through the marked location thereby \u2018teaching\u2019 various paths which are recorded in the computer and recalled later when the wheelchair is in use.