There are multiple definitions:

1. retinal pigment epithelium(English)

   • FAF, OCT
   • Ophthalmology

2. rating of perceived exertion(English)

   • cardiopulmonary exercise testing; see Borg scale
   • RER, CR10
   • Exercise & Training, Stress (test), Scoring systems/scales
   • https://pubmed.…h.gov/11708692/

3. rapid palatal expansion(English)

   • refers to low-level laser therapy
   • LLLT, MPS, MSW
   • Dentistry, Laser technique
   • https://doi.org…72/jlms.2022.13
   • https://doi.org…72/jlms.2020.S6