Thanx everybody. Bill I was in the right direction as I thought it was an imaginery line just to
pull the stab, wing & engine incidence together with one another. On mounting the wing an setting the incidence from there I have heard that it is better to mount the stab an set everthing else from the stab. Any truth to that? Anyway thanx for confirming that the datum line is an
imaginery reference point now on to building.