as for a literal description... SAS is the British Special Air Service, or in Austrailia and many other former British colonies (SASR) Special Air Service Regiment. They are the Royal Army special operations guys. They are analogous to US Special Forces, while the SBS (Special Boats Squadrons) are the Royal Navy/Royal Marines version, more analogous to SEALs or Marine Force Recon. The SAS also has an elite squad within the elite who specialize in Counter-Terrorism, I can't remember their name off the top of my head but they're equivalent to the US Special Forces Operational Detachment- Delta aka Delta Force or SEAL Team Six aka DevGroup (who call themselves Jedi). That's SAS in a nutshell... I could go on forever.