/...It does stand for wireless transmitter, and has to do with the fact that all moving surfaces have to be electrically grounded to each other, "bonded" is the proper term, because different surfaces will build up different electrostatic charges otherwise. Hinges and bearings are not a good enough path, so small braided wires are installed to join moving surfaces to main structure. In the absence of the bonding connections static discharge will take place, particularly in precipitation, making radio communication difficult or impossible because the static discharge is in the radio frequency range of the electromagnetic spectrum.../
/...The W/T was a stencil, used as an inspection stamp, to show that the earthing had been tested.../
source par exemple: http://cs.finescale.com/fsm/modeling_su ... 79642.aspx
Selon les sources : Wireless Transmitter, ou Wired Throughout, ou Wireless Telegraphy, mais le principe reste le même.