Most triggers use a small flattened lever (called the "trigger blade") depressed by the index finger, but some weapons such as the M2 Browning machine gun or the Iron Horse TOR ("thumb-operated receiver") use a push-button-like thumb-actuated trigger design, and others like the Springfield Armory M6 Scout use a squeeze-bar trigger similar to the "ticklers" on medieval European crossbows. Although the word "trigger" technically implies the entire mechanism (known as the "trigger group"), colloquially it is usually used to refers specifically to the trigger blade.