Percival P.40 Prentice T.1
 

me again, hoping to find someone that knows what this stencil means, also on the upturned wing tip of operational aircraft

Guessing here, but PAC is probably Percival Aircraft Company, with the /F and /R being /Fin and /Rudder perhaps? The marking between the black lines may be where the gust lock clamps may fitted i.e Clamp here, which may also apply to wingtip ailerons.

Ask in the History & Nostalgia forum. Not much in that forum that doesn't come up aces.

thanks Cpt Pugwash, i should have know that after going blind looking at of aircraft stencils, sometime ya can't see the wood for the trees

Yep it will be clamp here, you can see the gustlock lines on the front of the fin too, it will be over a hard point on the rudder i.e, a rib, which is where the hinge is attached, If the F and R are not the obvious, they may refer to the finish, one being cellulose paint and the other silver doped, what's under the wing?