Keys
– 1/2 inch square keys
– 1/4 inch spacing between keys
– slight concave surface
– matte finish to reduce glare finger slippage
– 40- to 125-gram force to activate
– 3 to 5 millimeters displacement
– tactile and audible feedback important
– certain keys should be larger (e.g. ENTER, SHIFT, CTRL)
– some keys require state indicator, such as lowered position
or light indicator (e.g. CAPS LOCK)
– key labels should be large, meaningful, permanent
– some "home" keys may have additional features, such as
deeper cavity or small raised dot, to help user locate their
fingers properly (caution - no standard for this)