Microsoft GUID (********-****-****-****-************)
5x5 (*****-*****-*****-*****-*****)
Use random chars
Use letters
UPPER CASE (A-Z)
low case (a-z)
Use numbers (0-9)
Use additional chars ( )
User's chars (put without any delimiters) 
Use prefix 

Use mask with  as wild char
Limited by length
 Minimal password length
 Maximum password length