An off-route obstruction clearance altitude (OROCA) is an off-route altitude that provides obstruction clearance with a 1,000-foot buffer in non-mountainous terrain areas, and a 2,000-foot buffer in designated mountainous areas.
It can be found on US IFR low charts and VFR sectionals, as seen here.
References:
1. “You Should Know These 10 Minimum IFR Altitudes” by BoldMethod
