Extends the units.xsd and basicTypes.xsd schemas with types for recording measures using specific types of units, especially the measures and units needed for coordinate reference systems and coordinate operations. The specific unit types encoded are length, angle, scale factor, time, area, volume, speed, and grid length. This schema allows angle values to be recorded as single numbers or in degree-minute-second format.
Parts of this schema are based on Subclause 6.5.7 of ISO/CD 19103 Geographic information - Conceptual schema language, on Subclause A.5.2.2.3 of ISO/CD 19118 Geographic information - Encoding, and on Subclause 4.7 of OpenGIS Recommendation Paper OGC 02-007r4 Units of Measure Use and Definition Recommendations.
GML is an OGC Standard.
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Value of a length (or distance) quantity, with its units. Uses the MeasureType with the restriction that the unit of measure referenced by uom must be suitable for a length, such as metres or feet.
Value of a scale factor (or ratio) that has no physical unit. Uses the MeasureType with the restriction that the unit of measure referenced by uom must be suitable for a scale factor, such as percent, permil, or parts-per-million.
Value of a time or temporal quantity, with its units. Uses the MeasureType with the restriction that the unit of measure referenced by uom must be suitable for a time value, such as seconds or weeks.
Value of a length (or distance) quantity in a grid, where the grid spacing does not have any associated physical units, or does not have a constant physical spacing. This grid length will often be used in a digital image grid, where the base units are likely to be pixel spacings. Uses the MeasureType with the restriction that the unit of measure referenced by uom must be suitable for length along the axes of a grid, such as pixel spacings or grid spacings.
Value of a spatial area quantity, with its units. Uses the MeasureType with the restriction that the unit of measure referenced by uom must be suitable for an area, such as square metres or square miles.
Value of a spatial volume quantity, with its units. Uses the MeasureType with the restriction that the unit of measure referenced by uom must be suitable for a volume, such as cubic metres or cubic feet.
Value of a speed, with its units. Uses the MeasureType with the restriction that the unit of measure referenced by uom must be suitable for a velocity, such as metres per second or miles per hour.
Value of an angle quantity provided in either degree-minute-second format or single value format.
Value of an angle quantity recorded as a single number, with its units. Uses the MeasureType with the restriction that the unit of measure referenced by uom must be suitable for an angle, such as degrees or radians.
Angle value provided in degree-minute-second or degree-minute format.
Integer number of degrees, plus the angle direction. This element can be used for geographic Latitude and Longitude. For Latitude, the XML attribute direction can take the values "N" or "S", meaning North or South of the equator. For Longitude, direction can take the values "E" or "W", meaning East or West of the prime meridian. This element can also be used for other angles. In that case, the direction can take the values "+" or "-" (of SignType), in the specified rotational direction from a specified reference direction.
Integer number of degrees in a degree-minute-second or degree-minute angular value, without indication of direction.
Decimal number of arc-minutes in a degree-minute angular value.
Integer number of arc-minutes in a degree-minute-second angular value.
Number of arc-seconds in a degree-minute-second angular value.