In academic and medical circles, a file designated as b391 (specifically PRSGO/B391 ) refers to a virtual surgical planning video. Maxilla rotation and cleft palate surgery.
Some Microsoft Learn documentation or XML sitemaps use b391 as a temporary locator for video content locations .
Below are the most prominent "features" associated with this specific identifier as of April 2026: 📽️ Surgical Training & Medical Media