Well the first would be that you own it and you have the original order sheet, build communication and receipt. The next best is that you bought from the original owner, you have all that stuff and the receipt to you and a statement from the owner as to the period of their ownership. And so on.
I have found reconstructing this to be difficult. Neither Peter Weigle or Richard Sachs will own up to my Witcomb. Or venture a guess as to the the possible third party. And why in the world should they remember, some fine points of construction from thirty years ago.
The purpose of my inquiry is to compile a definitive "best of all possible worlds" list of items should be in a bicycles provenance.
I honestly don't know - I can speculate, of course; but, I don't know what serious collectors consider an ideal provenance.
Make, model, builder, materials, angles, year, re-sprays, owners, etc ? I truly don't know.
As long as some previous owners and builders are still among the quick, I may as well going about things in the proper manner.
Chicago, Illinois; U.S.A.