Which are the basic rules for .gr domain names with greek characters?

There are 3 basic rules for creating domain names with greek characters:

a. Domain names containing both greek and latin characters at the same level can be supported, such as myφως.gr
b. There is no difference between characters σ and ς, for example φαροσ.gr and φαρος.gr
γ. There is no difference between lowercaseor uppercase unstressed greek characters and lowercase or uppercase stressed greek characters π.χ. ματινα.gr, MATINA.GR, ματίνα.gr, ΜΑΤΊΝΑ.GR