It looks like the 10mm loops at 'random pipe' and perhaps continues to disconnected gas clamp. Was thinking C3 for JB until I realised it's under the units!
That may be the case, but somehwere along the line it may be connected to the water as well (as only one main bond in MET), but I cant be certain of that. I will code the disconnected gas bonding as a C2 and I think the 'unfound' water bonding as 'further investigation', as it may or may not be connected to the MET by a 10mm.
Thanks for the replies guys, I'm glad I was pretty much on the right lines.