Marathon Internal Engineering Documents Section 1-c appendix H Subject: Doors By: Estasia Orestes, Dominick I. Plackar, and Ursa Simbalzi Date:<2402.03.23.16.42> There are five basic door designs to be used on the Marathon: 1. Outer Bulkhead Doors 2. Airlock Doors 3. Inner Bulkhead Doors 4. Tertiary or Inner Sealed Non-Vacuum Safe Doors 5. Quaternary or Inner Powered Automatic Opening Doors The tertiary and quaternary doors are designed exactly as the bulkhead doors, but are checked coarsely for air leakage.