now we're getting somewhere...
A point system sounds like a good idea - the only down side I see is if management or someone doesn't like you they might not allocate you the deserving points you might earn on experience etc.
Again- I agree with "the best man for the job" - when a position is available, advertise and do the interviews of applicants. As with any position, internally advertised first, then look external. Perhaps a seniority "list" could be kept simply for "seniority in service to the company" etc - not determining your next position, but will be used when allocating leave (if you need to bid for leave over the typical holiday season) or similar situations .. or who gets the front seat in the crew bus.. (JOKE!)
Whatever the use, I think companies could use such a list wisely and benefit both sides - but I wouldn't use it to just shift someone into the LHS when he's number is up...
my 5 cents worth.