तलएक्षण (levelling) कार्य में, 'स्टेशन' को उस स्थान के रूप में परिभाषित किया जाता है जहां:

Seven consecutive readings taken with a levelling instrument are 1.345, 1.525, 0.785, 1.105, 1.855, 2.005, and 1.985. If the instrument was shifted after the third and fifth readings, the readings recorded in the Back Sight (BS) column would be:

In levelling, the line of collimation is known as ___________.