There are 3 unique codex entries in the Achievement: Datacrons section on Ossus. They are accessible to all players regardless of class or faction.
Odan-Urr is obtained from interacting with the +6 Red Mastery datacron.
Codex type: Achievement: Datacrons | Faction: Both | Class: All
Associated Achievement: None
Ood Bnar | Coordinates: 1375, -461 | Location: Ossus: Ancient Ruins
Ood Bnar is obtained from interacting with the +2 Green Endurance datacron.
Codex type: Achievement: Datacrons | Faction: Both | Class: All
Associated Achievement: None
Odan-Urr is obtained from interacting with the +5 Yellow Presence datacron.
Codex type: Achievement: Datacrons | Faction: Both | Class: All
Associated Achievement: Nar Shaddaa Datacron Master