A third aspect of the invention provides a shim for arrangement against a structural component, the shim having a shim surface which is provided with {TAIL ~ a first feature} defining opposite ends spaced apart by first distance and a second feature spaced from the first feature defining {HEAD ~ opposite ends} spaced apart by a second, different distance 
A third aspect of the invention provides a shim for arrangement against a structural component , the shim having a shim surface which is provided with { TAIL ~ a first feature } defining opposite ends spaced apart by first distance and a second feature spaced from the first feature defining { HEAD ~ opposite ends } spaced apart by a second , different distance
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH