These SANBs (as they are known) are the workhorses of the world's airlines; with a nominal seating capacity from 100 to 210 seats, they are more versatile than their wide-body, jumbo cousins.
SANBs such as Boeing's 737 and Airbus's A320 families, powered by twin 30,000-pound-thrust engines from CFM International (a collaboration of General Electric and Snecma) or from International Aero Engines (a collaboration of Pratt & Whitney, Rolls-Royce, MTU, and Japanese Aero Engines Corp.
The SANB market has been the most lucrative for engine manufacturers.
Regional jet maker Bombardier is entering into the main line SANB market with its 110-130 seat CSeries.
All current and potential new SANB entrants have been enabled by one key factor: the arrival of new engine technology from Pratt & Whitney and CFM International.
The PW1000G will be 15% more fuel efficient and markedly quieter  than current engines used on regional and SANB jets.
CFM International's LEAP-X engine will power ABC (Airbus, Boeing and COMAC) SANB aircraft.
What about SANB aircraft development, beyond the next twenty years?