1. The chainage of staff stations are continuous from beginning to the end of the section line. 2. Readings of B.S. and F.S. should be taken very accurately with the bubble exactly in the center of its run. 3. To eliminate the instrumental error, the back sight and fore sight distance should be approximately equal. 4. The features such as nalla, river, road, canal etc. crossed by the line should be fully located by taking bearing of their centre lines, their width or by offset. 5)All the temporary adjustments at all instrument position shall carefully be done.