🚀 go-pugleaf

I believe the best method is to take a description to a notary (or perhaps
two young ones, in case one dies) and have your signature notarized on each
page of the description.  Leave space for the notary's seal at the bottom,
so that no essential details are obscured.  Have the notary keep a copy
(they usually do anyway), and specify how long you think the information
might be important.  It might be worth having the notary keep a copy
in a sealed envelope to counter claims of fiddling notarial files.

My Uncle Paul, a fairly prolific inventor (of teflon-coated bullet fame),
makes regular trips to the notary with sheafs of paper.

IBM uses an interesting system: you are required to keep notes of your work
in special IBM notebooks.  At the end of the day, you sign and date all
the pages you used that day.  These notebooks have been important evidence
at patent infringement trials.  If you use such a system, get bound books
of lined paper, like the green books the government issues.  Spiral and
loose-leaf books are much less persuasive, for obvious reasons.