Obviously it's not my 4001st render...
Here's how my coding system works.
0001-2000 - Signatures
2001-4000 - Avatars
4001-6000 - Renders
7001-9999 - Photos that can be rendered
It makes searching for stuff way easier. And I put this in an excel file also with all the players featured in that particular graphic (so I can filter/sort) my collection.