Fiberoptics can be employed to detect downhole electromagnetic signals via resistive heating. In a market for a particular type of instrument, buy orders and sell orders are received from a plurality of traders. After a time interval the system learns a second position from the GPS at a second time. In the supporting position, the armrest core may be adjacent a ribs of an occupant and, in the deployed position, the armrest core may be adjacent the hips of the occupant.