Identify the biggest (or longest) of the main survey lines in chain surveying.
Base Line:- The line on which the framework of the survey is built is known as the baseline. It is the most important line of the survey.
Generally, the longest of the main survey lines is considered the baseline.
This line should be taken through fairly level ground and should be measured very carefully and accurately. The magnetic bearings of the baseline are taken to fix the north line of the map.