Taken from
www.tripleaughtdesign.com/glossary.htm
LOCKING MECHANISMS
1) LOCKING LINER - this particular locking system was refined by knifemaker Michael Walker. The actual locking mechanism is incorporated in the liner of the handle, hence the name. If there is a metal sheet inside the handle material, it is called a liner. With a locking liner, opening the blade will allow this metal will flex over and butt against the base of the blade inside the handle, locking it open. Moving this liner aside will release this lock allowing the blade to close. Disengagement of the lock is performed with the thumb, allowing for one handed, hassle free action. Locking liners are commonly found on tactical folders, both production and custom.
2) LOCK BACK - a "tried and trued" blade locking system where the "back" of a folding knife pivots or seesaws to lock a blade open. A pair of nesting notches in the back spacer and blade facilitates the locking action. The lock back is released by pressing down and pivoting the back spacer notch up and above the blade. While considered more secure than a liner lock, the process of unlocking often requires both hands.
3) FRAME LOCK - a locking system derived from the "liner lock" where the leaf or "liner" is actually part of the handle. Commonly found in folders where no scales are used and the handles are solid slabs of titanium.
4) BUTTON LOCK - a locking system where the blade is held open and locked in place by a plunge shaft. The lock is engaged and disengaged by a "button" at one end of this shaft exposed on the handle side. This type of lock is considered exceptionally strong if engineered correctly. Due to more complex nature of this type of lock it is not as common as the liner type locking systems.