The term frame describes the "ribs" of a vessel or main lateral bulkheads within a ship.
In the Colonial Fleet, frames refer to the ribs that form structural segments of a battlestar. These major structural bulkheads provide structural strength as well as serve as dividers within the vessel's interior space into airtight compartments. Frames form a damage control against hull breaches that could vent atmosphere, equipment or crew into space. Frames help contain decompression within small compartments or bays.
Often when discussing areas of the ship, frame numbers are used to quickly define sections of a vessel.