Some of the varieties I grow most often, and are most treasured, are kept in a sort of family tree file. I confess that it is not always up to date, but it can easily be updated from my annual growing logs and my seed collection file.
Here is an example:
For Cherokee Chocolate, the variety appeared in 1995 when growing out Cherokee Purple that was saved in 1991. (In 1991, my saved Cherokee Purple was put in vial number 27 - my code therefore is 91-27). The seed from the chocolate colored tomato was stored in vial 47 - so the "parent" of Cherokee Chocolate is 95-47.
I grew out a few plants in 1996 - two out of three produced the chocolate colored tomatoes, the other purple. Seeds from one of the chocolate colored fruit were saved in vial number 3 - so the code is 96-3. I actually went back to that vial in 2007, and seed from the chocolate fruit from that plant were stored in vial 11 - so the code is 07-11 for my Cherokee Chocolate that year.
So between 1995, when Cherokee Chocolate first appeared in my garden, and this year, I have Cherokee Chocolate seed saved with about 30 different codes that point to the year I grew the tomato that produced the seed and the vial number.
Just as an aside - and a topic for another blog entry - I sent out some of the 1996 saved seed (not sure if it was vial 96-3 or 96-9) to Darrell Merrill (a great SSE member who is, sadly, no longer with us) in Oklahoma. Darrell grew it out and returned fresh seed to me. In 1997, one of the plants that came from the seed he sent was the start of the Cherokee Green line! But that's another story...
Below is what my Cherokee Chocolate page looks like (it's not very pretty, but it is useful to me!)