History Abbreviations and Acronyms

1. OPAL
   Oriental Philatelic Association of London
2. OPRHP
   Office of Parks Recreation and Historic Preservation
3. OPRS
   Old Parochial Records
4. OPS
   Office of Price Stabilization
5. OPS
   One-Place Studies
6. OPW
   Office of Public Works
7. ORB
   On-Line Reference Book
8. ORB
   Online Resource Booking
9. ORBS
   Operations Record Books
10. ORC
    Order of Railroad Cocductors
11. ORC
    Order of Railway Conductors
12. ORHPA
    Oak Ridge Heritage and Preservation Association
13. ORI
    Office of Road Inquiry
14. ORIA
    Ord River Irrigation Area
15. ORIAS
    Office of Resources for International and Area Studies
16. ORO
    Oxfordshire Record Office
17. OROM
    Opuscula Romana
18. ORRRC
    Outdoor Recreation Resturces Review Commission
19. OS
    Old Series
20. OS
    Ordnance Survey

Last updated: May 24, 2020 — Total entries: 3,857