THey refer to male or female or unknown
for example:
1.0 cornsnake - 1 male cornsnake
0.1 cornsnake - 1 female cornsnake
sometimes you'll also see:
0.0.1 cornsnake - means sex unknown
Right now in my household I have:
1.0 Normal Ball Python het Albino (Male)
0.0.1 California King Snake (Unknown)
0.0.1 Spotted Python (Unknown)
3.4 Cornsnakes (3 boys, 4 girls)
6.5 Siamese Cats (6 boys, 5 girls)
1.0 Dog (1 boy)
1.1 Children (1 boy, 1 girl)
1.0 Fiance (1 boy LOL)
A little more clear?