Global Ordnance
The new system used to spawn heavy weapons onto the map. Whereas past Halo games spawned in weapons at specific points and times, only the initial spawn at the start of a match if fixed in Halo 4. After, ordnance spawns in at various, per-determined points on the map, with the game system rotating both the locations and weapons selected from those the designers made available on that map and game type. Spawned ordnance carries a waypoint, so all players in the game knows it has appeared.
Personal Ordnance
Used in Infinity Slayer (and available in other game modes via custom options) is an additional ordnance delivery method, initiated by individual players. Medals earned and their associated points contribute to filling an ordnance meter, which when filled prompts players to select from one of three randomly selected options. These options can include power ups, weapons and grenades. Once chose, the ordnance will spawn in near the player.