A lot of medical data processing is spread through a huge series of SQL and mainframe databases with lots of hacks to keep them roughly compatible.
A friend worked medical database where "sex" was a seven field containing values from {"F", "M", "Male", "woman"...} etc.
This is horrific but it's possible to imagine that it arose as a compromised between various equally terrible options...
Essentially, sex is biological while gender is social. Transsexuality is a disparity between what someone was born biologically as (sex) and what they identify as (gender).
See also: http://www.docstyles.com/apacrib.htm#AppA
A lot of medical data processing is spread through a huge series of SQL and mainframe databases with lots of hacks to keep them roughly compatible.
A friend worked medical database where "sex" was a seven field containing values from {"F", "M", "Male", "woman"...} etc.
This is horrific but it's possible to imagine that it arose as a compromised between various equally terrible options...