Laws of Cricket 1947 Code - Law 19
The score shall be reckoned by runs. A run is scored:
1st So often as the Batsmen after a hit, or at any time while the ball is in play, shall have crossed and made good their ground from end to end; but if either Batsman run a short run, the Umpire shall call and signal "One short" and that run shall not be scored. The Striker being caught, no run shall be scored; a Batsman being run out, that run which was being attempted shall not be scored.
2nd For penalties under Laws 21, 27, 29, 44, and boundary allowances under Law 20.
Notes on Law 19
1. If while the ball is in play, the batsmen have crossed in running, neither returns to the wicket he has left except in the case of a boundary hit, or under Laws 30 Note 1 and 46 Note 4 (vii). This rule applies even should a short run have been called, or should no run be reckoned as in the case of a catch.
2. At his own risk the striker may take guard and play the ball in front of the popping crease; should he attempt to run from that point, the umpire does not call "One short".
3. If two or more runs are attempted, only one run is deducted on a call of "One short", even though both batsmen may have failed to complete the same run, and although the failure of a batsman to complere a run shortens the run immediately following.
4. The umpire signals "One short" by bending an arm upwards to touch the shoulder with the tips of the fingers.
Reproduction of the Laws of Cricket is by kind permission of Marylebone Cricket Club