The temporal schema for GML 3.0 provides constructs for handling time-varying spatial data. This schema reflects a partial yet consistent implementation of the model described in ISO 19108 (topological complexes and feature succession are not included). Copyright (c) 2002 OGC, All Rights Reserved. This abstract element acts as the head of the substitution group for temporal primitives and complexes. A temporal object must be associated with a temporal reference system via URI. The Gregorian calendar with UTC is the default reference system, following ISO 8601. Other reference systems in common use include the GPS calendar and the Julian calendar. This abstract element acts as the head of the substitution group for temporal primitives. The abstract supertype for temporal and topological primitives. An association with a gml:TimeInstant element at the end. This abstract element serves as the head of the substitution group for elements used to indicate temporal length or distance (duration, interval). Base type for describing temporal length or distance. The value space is further constrained by subtypes that conform to the ISO 8601 or ISO 11404 standards. This element is an instance of the primitive xsd:duration simple type to enable use of the ISO 8601 syntax for temporal length (e.g. P5DT4H30M). It is a valid subtype of TimeDurationType according to section 3.14.6, rule 2.2.4 in XML Schema, Part 1. Here we have collapsed the hierarchy of subtypes for temporal position in 19108 by defining a union of simple types for indicating temporal position relative to a specific reference system. Date and time may be indicated with varying degrees of precision: year, year-month, date, or dateTime (all ISO 8601 format). Note that the dateTime type does not allow right-truncation (i.e. omitting seconds). An ordinal era may be referenced via URI, and a decimal value can be used to indicate the distance from the scale origin (e.g. UNIX time, GPS calendar). Direct representation of a temporal position. Indeterminate time values are also allowed, as described in ISO 19108. The indeterminatePosition attribute can be used alone or it can qualify a specific value for temporal position (e.g. before 2002-12, after 1019624400). For time values that identify position within a calendar, the calendarEraName attribute provides the name of the calendar era to which the date is referenced (e.g. the Meiji era of the Japanese calendar). This enumerated data type specifies values for indeterminate positions. This element is a valid subtype of TimeDurationType according to section 3.14.6, rule 2.2.4 in XML Schema, Part 1. This type extends the built-in xsd:decimal simple type to allow floating-point values for temporal length. According to the ISO 11404 model you have to use positiveInteger together with appropriate values for radix and factor. The resolution of the time interval is to one radix ^(-factor) of the specified time unit (e.g. unit="second", radix="10", factor="3" specifices a resolution of milliseconds). It is a subtype of TimeDurationType. This enumerated data type indicates standard units for measuring time. A timestamp property associates an element with a temporal primitive. A value in the time domain is measured relative to a temporal reference system. Common types of reference systems include calendars, ordinal temporal reference systems, and temporal coordinate systems (time elapsed since some epoch, e.g. UNIX time). A temporal coordinate system is based on a continuous interval scale defined in terms of a single time interval. In an ordinal reference system the order of events in time can be well established, but the magnitude of the intervals between them can not be accurately determined (e.g. a stratigraphic sequence). Ordinal temporal reference systems are often hierarchically structured such that an ordinal era at a given level of the hierarchy includes a sequence of shorter, coterminous ordinal eras.