Steps" sequence being oft-referenced in later movies. The Doctor is IN 19a est. {It's not exact: Abbr.}. est. short for estimate. 22a Osage {Dakota relative}. Osage and Dakota tribes. 27a ASL {Special communication syst.}. American Sign Language . 44a SLA {Radical 1970s grp.}. Symbionese Liberation Army , kidnappers of Patty Hearst