This is always used to note the sexes of reptiles of the same species and sub-species.
So, if you have 1 male and 2 female royalls, you would write:
1.2.0 royal pythons
Or, you may drop the unsexed column if it is not needed
1.2 royal pythons
If you have 1 male and 1 female and 6 of undetermined sex, you would write: 1.1.6
If you only have 6 of undetermined sex, you would write: 0.0.6