Mädi is a german nickname standing for "little girl". She ist very small and the mother of Maybe, who is taller than she is.
The mark in her ear means that she has been neutered. So if somebody catches her from any animal shelter organisation, they will know that she has a home and is taken care of. At the time when I got all those cats identification chips were still very expensive and not all vets offered them and tattoos fade after a while