Numeric shift
Provided by the ASK Keyboard Dictionary
Aka/also known as: num shift, upper shift
Numeric shift was a key on IBM data entry (DE) terminal keyboards used to access numbers, operators and symbols that were printed at the top of a keycap's face (hence the alternate name "upper shift"). When present, the numeric shift took the place of the left shift key and was presented by an upright shift arrow symbol (as such, it shouldn't be confused with shift keys on typewriter-style terminal and PC keyboards).