DNS_LOC_DATA

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Windows Embedded CE 6.0 R3

4/8/2010

This structure represents a DNS location (LOC) record.

Syntax

typedef struct {
  WORD wVersion;
  WORD wSize;
  WORD wHorPrec;
  WORD wVerPrec;
  DWORD dwLatitude;
  DWORD dwLongitude;
  DWORD dwAltitude;
} DNS_LOC_DATA, *PDNS_LOC_DATA;

Members

• wVersion
  [in] Version number of the representation. Must be zero.

• wSize
  [in] Diameter of a sphere enclosing the described entity, in centimeters, expressed as a pair of four-bit unsigned integers, each ranging from zero to nine, with the most significant four bits representing the base and the second number representing the power of ten by which to multiply the base. This format allows sizes from 0e0 (<1cm) to 9e9 (90,000km) to be expressed.

• wHorPrec
  [in] Horizontal precision of the data, in centimeters, expressed using the same representation as wSize. This is the diameter of the horizontal circle of error, rather than a plus or minus value. Matches the interpretation of wSize; to get a plus or minus value, divide by 2.

• wVerPrec
  [in] Vertical precision of the data, in centimeters, expressed using the same representation as wSize. This value represents the total potential vertical error, rather than a plus or minus value. Matches the interpretation of wSize; to get a plus or minus value, divide by 2.

  If altitude above or below sea level is used as an approximation for altitude relative to the [WGS 84] ellipsoid, the precision value should be adjusted.

• dwLatitude
  [in] Latitude of the center of the sphere described by wSize, expressed as a 32-bit integer, with the most significant octet first (network standard byte order), in thousandths of a second of arc. 2^31 represents the equator, larger numbers are north latitude.

• dwLongitude
  [in] Longitude of the center of the sphere described by wSize, expressed as a 32-bit integer, most significant octet first (network standard byte order), in thousandths of a second of arc, rounded away from the prime meridian. 2^31 represents the prime meridian, larger numbers are east longitude..

• dwAltitude
  [in] Altitude of the center of the sphere described by wSize, expressed as a 32-bit integer, most significant octet first (network standard byte order), in centimeters, from a base of 100,000m below the [WGS 84] reference spheroid used by GPS (semimajor axis a=6378137.0, reciprocal flattening rf=298.257223563). See Remarks for more information.

Remarks

This structure is used in conjunction with the DNS_RECORD structure to programmatically manage DNS entries.

For dwAltitude, altitude above or below sea level may be used as an approximation of altitude relative to the [WGS 84] spheroid, however, there will be differences due to the Earth's surface not being a perfect spheroid. For example, the geoid (which sea level approximates) for the continental US ranges from 10 meters to 50 meters below the [WGS 84] spheroid. Adjustments to dwAltitude and/or wVerPrec will be necessary in most cases. The Defense Mapping Agency publishes geoid height values relative to the [WGS 84] ellipsoid.

For more information about the LOC RR, see RFC 1876.

Requirements

See Also

Reference

DNS Structures