With these programmers you are able to edit transponders memory.
More info (eg. transponders memory structure) you will find in datasheets prepared by transponder manufactures.
Temic
Sokymat
Megamos
Philips PIT
Philips HITAG
Tiris
Write test for PCF7930/31/35
With this function you can check if transponder can be overwritten or is permanent locked.