1. A hand-held data collection terminal comprising: (a) a data collection terminal unit having an elongate body forming a hand-grip portion for use of the data collection terminal unit in a hand-held operating position; (b) said data collection terminal unit having a manually operated key arrangement comprising numerical keys and function keys, and a display screen; (c) said data collection terminal unit having a first side and a second side disposed laterally to each other; (d) said numerical keys and display screen being supported at the first side of the terminal unit; wherein: (e) at least one of the function keys is disposed on said second side of the terminal unit; and (f) a scanner module is selectively mounted to the terminal unit; (g) said at least one of said function keys being capable of operation as a scanner operation control key when the terminal unit is equipped with said scanner module.