There are multiple definitions:

1. European Hematology Association(English)

   • promotes excellence in patient care, research and education in hematology
   • Hematology, Organizations (scientific)
   • https://ehaweb.org/organization/

2. earth horizontal axis(English)

   • OOR, OVAR, ScOR, VOR
   • ENT
   • https://doi.org…8146(02)00117-7