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Copyright © 2010 Open Geospatial Consortium
7.8.4 Coordinate reference system handling
In filter expressions, geometric values shall be encoded using GML, as given in ISO 19136. In GML, the optional srsName attribute is used to specify the coordinate reference system for the coordinates of geometry.
Attention is drawn to the fact that specifications that reference this International Standard shall specify how to handle the following cases that can arise where two expressions that resolve to geometric values are
compared:
a the two geometry values have difference srsName values; b one or both of the geometry values do not have an srsName value specified.
Although this International Standard does not mandate what actions to take to resolve these situations, it is clear that some strategies for resolving these issues can require coordinate transformations to be applied to
one or both of the geometries.
7.9 Temporal operators 7.9.1 General considerations
A temporal operator see Figure 7 determines whether its time arguments satisfy the stated temporal relationship. The operator evaluates to true if the temporal relationship is satisfied. Otherwise, the operator
evaluates to false.
TemporalOperator + operatorType : TemporalOperatorName
+ operand1 : ValueReference + operand2 : TemporalOperand
+ After + Before
+ Begins + BegunBy
+ TContains + During
+ TEquals + TOverlaps
+ Meets + OverlappedBy
+ MetBy + EndedBy
+ AnyInteracts CodeList
TemporalOperatorName + temporalObject : TM_Object
+ valueReference : ValueReference Union
TemporalOperand
Figure 7 — TemporalOperator
Table 4 maps the temporal operators described in this International Standard to the set of temporal operators defined in ISO 19108.
Copyright © 2010 Open Geospatial Consortium
27 Table 4 — Mapping of ISO 19143 temporal operators to ISO 19108 temporal operators
ISO 19143 temporal operator ISO 19108 temporal operator
a After After
Before Before Begins Begins
BegunBy Begun TContains Contains
During During TEquals Equals
TOverlaps Overlaps Meets Meets
OverlappedBy OverlappedBy MetBy MetBy
EndedBy EndedBy AnyInteracts NA
a The values in this column are enumerates of TM_RelativePosition used in the relativePosition
operation from ISO 19108.
A service that implements this International Standard shall, in its filter capabilities see 7.14.5, declare which temporal operators it supports.
7.9.2 Encoding
The XML encoding for temporal operators is defined by the following XML Schema fragment:
xsd:element name=temporalOps type=fes:TemporalOpsType abstract=true xsd:complexType name=TemporalOpsType abstract=true
xsd:element name=After type=fes:BinaryTemporalOpType
substitutionGroup=fes:temporalOps xsd:element name=Before
type=fes:BinaryTemporalOpType substitutionGroup=fes:temporalOps
xsd:element name=Begins type=fes:BinaryTemporalOpType
substitutionGroup=fes:temporalOps xsd:element name=BegunBy
type=fes:BinaryTemporalOpType substitutionGroup=fes:temporalOps
xsd:element name=TContains type=fes:BinaryTemporalOpType
substitutionGroup=fes:temporalOps xsd:element name=During
type=fes:BinaryTemporalOpType substitutionGroup=fes:temporalOps
xsd:element name=EndedBy type=fes:BinaryTemporalOpType
substitutionGroup=fes:temporalOps xsd:element name=Ends
type=fes:BinaryTemporalOpType substitutionGroup=fes:temporalOps
xsd:element name=TEquals type=fes:BinaryTemporalOpType
substitutionGroup=fes:temporalOps xsd:element name=Meets
type=fes:BinaryTemporalOpType substitutionGroup=fes:temporalOps
xsd:element name=MetBy type=fes:BinaryTemporalOpType
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