measures.xsd v3.0 draft last updated 2002/04/19 GML 3.0 candidate schema. Copyright (c) 2002 OGC, All Rights Reserved. This schema extends the units.xsd and basicTypes.xsd schemas with elements for 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, and grid length. This schema allows angle values to be recorded as single numbers or in degree-minute-second format. Value of a quantity, with its units. The XML Schema primitive data type "double" is adapted because this single representation offers the greatest flexibility and precision. However, there is no requirement to store values using any particular format, and applications receiving elements of this type may choose to coerce the data to any other type as convenient. "uom" attribute is the reference to a unit of measure definition, usually within the same XML document but possibly outside the XML document which contains this reference. For a reference within the same XML document, the "#" symbol should be used, followed by a text abbreviation of the unit name. However, the "#" symbol may be optional, and still may be interpreted as a reference. 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. 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. 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. 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. 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. Angle value provided in degree-minute-second or degree-minute format. Number of degrees in a degree-minute-second or degree-minute angular value, with identification of the angle direction. The "N" or "S" values of direction are used for Latitude, and mean North or South of the equator. The "E" or "W" values of direction are used for Longitude, and mean East or West of the prime meridian. The "+" or "-" values of direction are used for other angles, in the specified rotational direction from the 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. Definition of a unit of measure (or uom) for a length (or distance). This element uses the UnitDefinitionType with the restriction that the unit must be suitable for a length, and thus use a base unit suitable for lengths. Definition of a unit of measure (or uom) for a scale factor (or ratio) that has no physical unit. This element uses the UnitDefinitionType with the restriction that the unit must be suitable for a scale factor, and thus use a base unit suitable for scale factors. Definition of a unit of measure (or uom) for a time or temporal quantity. This element uses the UnitDefinitionType with the restriction that the unit must be suitable for a time, and thus use a base unit suitable for times. Definition of a unit of measure (or uom) for a length 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 unit will often be used in a digital image grid, where the base units are likely to be pixel spacings. This element uses the UnitDefinitionType with the restriction that the unit must be suitable for lengths along the axes of a grid, and thus use a base unit suitable for grid lengths. Definition of a unit of measure (or uom) for an angle. This element uses the UnitDefinitionType with the restriction that the unit must be suitable for an angle, and thus use a base unit suitable for angles.