Indian standard time line is 82 1/2° eastern longitude. The major reason of regarding this as the standard time line is that this line is situated at the central point on the eastern and western extent of India. Apart from this, the internation time zone from 75° eastern longitude to 90° eastern longitude falls in the center of India. Therefore, the longitude between 75° eastern and 90° eastern longitudes amounts to 83°30′ eastern longitude. Due to this reason, it is regarded as the Standard Time Line. Its time is 5:30 hours ahead of the Greenwich Line.