Possible Clues:

• Hattiesburg-to-Nashville dir.
• Tulsa to K.C., for ex.
• Santa Fe-to-Colo. Spr. direction
• Little Rock-to-St. Louis dir.
• Reno-to-Boise dir.
• Bancroft to Pembroke dir.
• Frankfurt-to-Copenhagen dir.
• D.C.-to-Montreal heading
• Orienteering abbr.
• Tulsa-to-Topeka dir