There are multiple definitions:

1. A and B [points](English)

   • i.e. the angle formed by the nasion and these points
   • GTA, MMA, OSA, SNA
   • Dentistry, Sleep medicine
   • https://doi.org…oms.2014.10.018

2. anterior neural boundary(English)

   • CRM, GRN, pitx
   • Pituitary (gland), Anatomy, Nervous activity - (para)sympathetic
   • https://doi.org…bio.2004.10.008