There are multiple definitions:

1. oxygen extraction fraction(English)

   • the proportion of oxygen removed from the blood by tissues compared to the total amount of oxygen delivered to them
   • CBF, CMRO2, GFAP
   • Physiology, Oxygen, Brain (dys)function
   • https://doi.org/10.1113/JP291528

2. Operation Enduring Freedom(English)

   • BINT, DOD, mTBI, PTSD, TBI
   • Military medicine, Injury
   • https://www.ncb…/?report=reader