Bitragion Inion Arc 2 : The arc between tragion as measured over the inion; for test purposes, the bitragion inion arc is identified as Datum plane 10 in Figures 6-18. 4. 1(a) through (c)
NFPA 1976 Standard on Protective Ensemble for Proximity Fire Fighting, 2000 ed. https://www.nfpa.org/assets/files/AboutTheCodes/19 76/TIA1976-00-1.pdf, (Std: Prot Ens for Proximity Fr Fight - Amer) {430 NFC}