They are probably ID tags that the breeders use to label each snake. For example: If you had two pied females and one pied male in a clutch, you might use an alphanumeric designation for each snake containing the year hatched, morph, sex, and serial number. So they might look something like this: 10-PD-F-01, 10-PD-F-02, and 10-PD-M-01...
Our males get the little circle tabs. Their name, sex, year born and morph is the info we put on them... Hope this helps and I'm sure there are a bunch of different methods!