Info Source for Multi point Locks
Rory Snow of ALL ABOUT DOORS, INC has a wealth of information regarding atrium and patio doors with multiple point locks.
He has several pages of how they work. www.allaboutdoors.com gets you to the site, and if you have more questions you can contact Rory by email. (He'll never get anything done if you call him.) I got his initial contact information from Dave Thielen