Definition of datum line in English:

datum line

(also datum level)


  • 1A standard of comparison or point of reference.

    • ‘In a country where about 80 per cent of the population live below the poverty datum line, one could hardly expect the majority of parents to manage to pay the rising school fees.’
    • ‘And a statement from WEDAZ says Zambia has a total population of 10.2 million of which 73 per cent lived below the poverty datum line.’
    • ‘At R370 a month in 1993, and R470 in 1998, the pension kept its real value and exceeded the poverty datum line.’
    • ‘The question popping up now is: Just what has happened in the last six years to reduce the number of Zambian people wallowing below the poverty datum line - from 73 per cent in 1998 to 67 per cent as of August 2004?’
    • ‘Hard-hit are those in the lower income bracket, those who do not have any income at all, and those living below the poverty datum line (many other terms used for the poor).’
    1. 1.1Surveying An assumed surface used as a reference for the measurement of heights and depths.
      • ‘The Scope Leveler by Segway Industries uses the flat-top surface of the mount base, front or rear, as the horizontal datum line.’
      • ‘We have to make some choices when we dimension a block with a notch or cutout (figure 27). It is usually best to dimension from a common line or surface. This can be called the datum line of surface.’
      • ‘The biostratigraphic events reported by Bralower et al. were used for the definition of zonal boundaries, integrated with additional datum levels.’
      • ‘This system is generally fine until you have a very silty site, when a fixed datum line is a must.’
      • ‘There are three primary topographical conditions from datum line to datum line: floodplains and bottomlands in the river valleys, uplands midway between rivers and hilltops, and high land at the prevailing level of the plateau.’
    2. 1.2A line to which dimensions are referred on engineering drawings, and from which measurements are calculated.
      • ‘A set of calibrated marks and a vertical datum line coinciding with or parallel to the vertical suspension axis are imprinted on the plate above and below the hairline.’
      • ‘The street directory, consulted to verify this, revealed that a cul-de-sac called Swan Street in South Blackburn, some ten kilometres from the Other’ Swan Street, lies on the eastwards extension of this datum line.’