| 摘要 |
A picture of a plan view 4 of an area is displayed on a screen 24 of a base unit 2 of a measuring apparatus. The picture contains symbols 45 for respective traps disposed in the displayed area. A bar code is assigned to each trap for identifying it. When the bar code on one trap is read out, a marking "X" is added to the symbol 45 for that trap, so that an operator can readily know the location in the area of that trap on the display screen and, therefore, the current position of the operator in the area. <IMAGE> |
