English lowercase letters and digits of 3-15, subtract (-), underscore (_), a period (.) You can only use. (However, it is only the beginning and end of the inability to use, the disabled)
3-15 characters lowercase letters, numbers and minus (-), underscore (_), you can only use a period (.). (However, are not possible, only use numbers can not be used at the beginning and end)
3, 15, the english lowercase letters and numbers, a minus (-) and transverse (_), conclusion (.) can only be used. (however, the beginning and the end. the use of fire, the fire)