This property describes the minimum bounding box or rectangle that encloses the entire feature. deprecated Envelope defines an extent using a pair of positions defining opposite corners in arbitrary dimensions. The first direct position is the "lower corner" (a coordinate position consisting of all the minimal ordinates for each dimension for all points within the envelope), the second one the "upper corner" (a coordinate position consisting of all the maximal ordinates for each dimension for all points within the envelope). The use of the properties "coordinates" and "pos" has been deprecated. The explicitly named properties "lowerCorner" and "upperCorner" shall be used instead. This element has no type defined, and is therefore implicitly (according to the rules of W3C XML Schema) an XML Schema anyType. It is used as the head of an XML Schema substitution group which unifies complex content and certain simple content elements used for datatypes in GML, including the gml:AbstractGML substitution group. deprecated gml:NilReasonType defines a content model that allows recording of an explanation for a void value or other exception. gml:NilReasonType is a union of the following enumerated values: - inapplicable there is no value - missing the correct value is not readily available to the sender of this data. Furthermore, a correct value may not exist - template the value will be available later - unknown the correct value is not known to, and not computable by, the sender of this data. However, a correct value probably exists - withheld the value is not divulged - other:text other brief explanation, where text is a string of two or more characters with no included spaces and - anyURI which should refer to a resource which describes the reason for the exception A particular community may choose to assign more detailed semantics to the standard values provided. Alternatively, the URI method enables a specific or more complete explanation for the absence of a value to be provided elsewhere and indicated by-reference in an instance document. gml:NilReasonType is used as a member of a union in a number of simple content types where it is necessary to permit a value from the NilReasonType union as an alternative to the primary type. Direct position instances hold the coordinates for a position within some coordinate reference system (CRS). Since direct positions, as data types, will often be included in larger objects (such as geometry elements) that have references to CRS, the srsName attribute will in general be missing, if this particular direct position is included in a larger element with such a reference to a CRS. In this case, the CRS is implicitly assumed to take on the value of the containing object's CRS. if no srsName attribute is given, the CRS shall be specified as part of the larger context this geometry element is part of, typically a geometric object like a point, curve, etc. posList instances (and other instances with the content model specified by DirectPositionListType) hold the coordinates for a sequence of direct positions within the same coordinate reference system (CRS). if no srsName attribute is given, the CRS shall be specified as part of the larger context this geometry element is part of, typically a geometric object like a point, curve, etc. The optional attribute count specifies the number of direct positions in the list. If the attribute count is present then the attribute srsDimension shall be present, too. The number of entries in the list is equal to the product of the dimensionality of the coordinate reference system (i.e. it is a derived value of the coordinate reference system definition) and the number of direct positions. A type for a list of values of the respective simple type. The attribute group SRSReferenceGroup is an optional reference to the CRS used by this geometry, with optional additional information to simplify the processing of the coordinates when a more complete definition of the CRS is not needed. In general the attribute srsName points to a CRS instance of gml:AbstractCoordinateReferenceSystem. For well-known references it is not required that the CRS description exists at the location the URI points to. If no srsName attribute is given, the CRS shall be specified as part of the larger context this geometry element is part of. The attributes uomLabels and axisLabels, defined in the SRSInformationGroup attribute group, are optional additional and redundant information for a CRS to simplify the processing of the coordinate values when a more complete definition of the CRS is not needed. This information shall be the same as included in the complete definition of the CRS, referenced by the srsName attribute. When the srsName attribute is included, either both or neither of the axisLabels and uomLabels attributes shall be included. When the srsName attribute is omitted, both of these attributes shall be omitted. The attribute axisLabels is an ordered list of labels for all the axes of this CRS. The gml:axisAbbrev value should be used for these axis labels, after spaces and forbidden characters are removed. When the srsName attribute is included, this attribute is optional. When the srsName attribute is omitted, this attribute shall also be omitted. The attribute uomLabels is an ordered list of unit of measure (uom) labels for all the axes of this CRS. The value of the string in the gml:catalogSymbol should be used for this uom labels, after spaces and forbidden characters are removed. When the axisLabels attribute is included, this attribute shall also be included. When the axisLabels attribute is omitted, this attribute shall also be omitted. A type for a list of values of the respective simple type. deprecated This type is deprecated for tuples with ordinate values that are numbers. CoordinatesType is a text string, intended to be used to record an array of tuples or coordinates. While it is not possible to enforce the internal structure of the string through schema validation, some optional attributes have been provided in previous versions of GML to support a description of the internal structure. These attributes are deprecated. The attributes were intended to be used as follows: Decimal symbol used for a decimal point (default="." a stop or period) cs symbol used to separate components within a tuple or coordinate string (default="," a comma) ts symbol used to separate tuples or coordinate strings (default=" " a space) Since it is based on the XML Schema string type, CoordinatesType may be used in the construction of tables of tuples or arrays of tuples, including ones that contain mixed text and numeric values.