Thanks for all the input, I shall go and lie down in a dark room and curse my big mouth for opening it in the first place.
Mutt is quite correct I am trying to check one set of commercial data from a finished performance product against another set of obstacle data to proove the accuracy of the first (amongst other things). The idea being if the input data is correct and the software works then output data cannot be wrong!
This might be a simplistic attitude but I am a one-man-band with my own job to do apart from this "hot potato". Once the checking program is complete I hope to hand it to operations and let them deal with it.....
I was working on 1ft elevation and 30ft length as my margin for error (someone gave me those figures somewhere in the dim and distant past) but even using that I am still finding discrepancies. Both suppliers claim to be using the same source data in the same way.
I will sign up for the IATA database and see where that leads me.