There are lots of different ways to identify your different lead core rods. Some people make tags and write what they are on the tag and put the tags on the reels. I am an electrician by trade, and use the resister color code, and colored electrical tapes on my different lead core rods.
Black = 0
Brown = 1
Red = 2
Orange = 3
Yellow = 4
Green = 5
Blue = 6
violet = 7
gray = 8
white = 9
When I am pulling the rods out of the cabin to set up the boat for fishing, the colored tape is very visable without having to twist a rod around to see what number is written on a reel.
I put the electical tape just above the rod handle. In this image, you can see the orange tape on the rod just above the handle. Its a 3 color lead core.
If a rod is more than a full core, it will have a brown strip of tape and another strip of tape. If I have a 15 color core, it will have a brown strip of tape and a green strip of tape.
You do not have to use the color code I use, and you can get by with just a few different colors of tape.