F.I.L.S.S.

 F reelancer I ntegrated L ingestics and S ecruity S ystem, abbreviated F.I.L.S.S., is a computer system at the facility. It is embedded in a tree and allows clearance to the facility. Due to having a similar voice, Caboose calls "her" Sheila. She believes that Epsilon-Church is actually Dr. Leonard Church, the Director of Project Freelancer.

Trivia

 * The character Sheila originally called herself F.I.L.S.S. (originally thought to be spelled Phyllis) but Church mistakenly changed it to Sheila. It seems that Sheila was a secondary copy of F.I.L.S.S. but with less data on Project Freelancer that was used to monitor the Alpha on Blood Gulch.