From what I understand, it is for those who are biologically/genetically intersex.
Which, regardless of what is used in social justice circles that people seem to have latched onto, does exist in a medical way.
Intersex as used in this instance includes those that people call 'hermaphrodites' as well as those who have xxy genes (Klinefelter Syndrome) and other such chromosomal conditions.
Now stop being silly about gender.