The Frontier Accord was the formal agreement between the Federation and the Gorn Hegemony following the attack on Cestus III, which led to the end of hostilities between the two powers. (DS9 - Strange New Worlds I short story: "Where I Fell Before My Enemy")
This agreement was signed in 2281. (FASA RPG module: Star Trek IV Sourcebook Update).
- This story suggests a state of war still technically existed between the two power as late as 2372 (perhaps through the events of The Gorn Crisis).