<P> The most common and convenient datum which is internationally accepted is mean sea level . Countries take their nearby sea levels as datum planes for calculations of Reduced levels . For example , Pakistan takes sea near Karachi as its datum while India takes sea near Mumbai as its datum for calculation of Reduced levels of different places in their respective countries . The term Reduced Level is denoted shortly by ' RL ' . National survey departments of each country determines RL 's of significantly important locations or points . These points are called as permanent benchmarks and this survey process is known as Great Trigonometrical Surveying ( GTS ) . The permanent bench marks act as reference points for determining RL 's of other locations in a particular country . </P>
<P> The most common and convenient datum which is internationally accepted is mean sea level . Countries take their nearby sea levels as datum planes for calculations of Reduced levels . For example , Pakistan takes sea near Karachi as its datum while India takes sea near Mumbai as its datum for calculation of Reduced levels of different places in their respective countries . The term Reduced Level is denoted shortly by ' RL ' . National survey departments of each country determines RL 's of significantly important locations or points . These points are called as permanent benchmarks and this survey process is known as Great Trigonometrical Surveying ( GTS ) . The permanent bench marks act as reference points for determining RL 's of other locations in a particular country . </P>
the datum adopted in india is the mean sea level at
the datum adopted in india is the mean sea level at
Mumbai
Mumbai