Dr. Farrell invented the method & coding they use for freeze branding the mustangs etc. After he passed away his wife, Pat, started Kyro Kenetics. I know she sold the "business" many years ago so don't know if it is still registered with every state anymore or not. If the horse was registered it was given it's registration number. If not, a letter for the state followed by a number (code) on the crest of the neck. The horses were just held by a twitch with a towel over their eyes. All the horses we had (still have one old mare) were freeze branded. The white ones the iron stayed on long enough to kill the hair.
Hope this helps,