What does HX stand for?

What does HX mean?

Hx	History Community » Educational
Hx	Medical History Medical » Physiology
Hx	Medical History Medical » Hospitals
Hx	Medical History Medical » Oncology
Hx	Medical History Medical » Laboratory
Hx	Medical History Governmental » FDA
HX	Herding Excellent Miscellaneous » Dogs Related
HX	Halifax Corporation Business » AMEX Symbols
HX	THOR database Cross-reference Hsh file Computing » File Extensions
HX	Herc Xena Miscellaneous » Unclassified
HX	Halifax (WW II Convoy Route) Governmental » Military
HX	Hyper Xtream Computing » Software
HX	Heat Exchanger Governmental » NASA