In reply to Steve Wetton:
I have been considering the points raised by Owen's thread and came to this conclusion:
If a route goes A, B, C, D and that is the line taken by the FA then that is the route, let us call it "First route" E4.
If someone comes along and climbs A, B, C, D and finds a hold or undercut missed by the FA then it is still "First Route" but they grade may drop a point. If a hold falls off then it may go up a point.
If someone comes along and climbs A, B, E, D missing out the hard C section by drifting right to the easier E section then they have not climbed "First route", they have climbed a "First route variation" or if they do A, B, E, F then possibly even a new route with the same starting point.
In the past if a bolted or aided climb was freed then it was given a new name. The same should apply to a trad climb that has been retro bolted (not that we are talking about this I am just thinking out loud here), in order to avoid confusion.
Avoiding confusion is the main point. Any deviation from the original line is a variation on the original route to a greater or lesser extent. If the FA went one way and everyone else goes another then they may be going up a better line on the rock but they are not climbing the same route