| Rfc | 7035 |
|---|
| Title | Relative Location Representation |
|---|
| Author | M. Thomson, B. Rosen, D. Stanley,
G. Bajko, A. Thomson |
|---|
| Date | October 2013 |
|---|
| Format: | TXT, HTML |
|---|
| Status: | PROPOSED STANDARD |
|---|
|
Internet Engineering Task Force (IETF) M. Thomson
Request for Comments: 7035 Microsoft
Category: Standards Track B. Rosen
ISSN: 2070-1721 Neustar
D. Stanley
Aruba Networks
G. Bajko
Nokia
A. Thomson
Lookingglass
October 2013
Relative Location Representation
Abstract
This document defines an extension to the Presence Information Data
Format Location Object (PIDF-LO) (RFC 4119) for the expression of
location information that is defined relative to a reference point.
The reference point may be expressed as a geodetic or civic location,
and the relative offset may be one of several shapes. An alternative
binary representation is described.
Optionally, a reference to a secondary document (such as a map image)
can be included, along with the relationship of the map coordinate
system to the reference/offset coordinate system, to allow display of
the map with the reference point and the relative offset.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7035.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction ....................................................4
2. Conventions Used in This Document ...............................4
3. Overview ........................................................4
4. Relative Location ...............................................7
4.1. Relative Coordinate System .................................8
4.2. Placement of XML Elements ..................................8
4.3. Binary Format ..............................................9
4.4. Distances and Angles .......................................9
4.5. Value Encoding ............................................10
4.6. Relative Location Restrictions ............................10
4.7. Baseline TLVs .............................................10
4.8. Reference TLVs ............................................10
4.9. Shapes ....................................................11
4.9.1. Point ..............................................11
4.9.2. Circle or Sphere Shape .............................12
4.9.3. Ellipse or Ellipsoid Shape .........................13
4.9.4. Polygon or Prism Shape .............................15
4.9.5. Arc-Band Shape .....................................18
4.10. Dynamic Location TLVs ....................................20
4.10.1. Orientation .......................................20
4.10.2. Speed .............................................20
4.10.3. Heading ...........................................20
4.11. Secondary Map Metadata ...................................21
4.11.1. Map URL ...........................................21
4.11.2. Map Coordinate Reference System ...................21
4.11.3. Map Example .......................................24
5. Examples .......................................................24
5.1. Civic PIDF with Polygon Offset ............................24
5.2. Geo PIDF with Circle Offset ...............................26
5.3. Civic TLV with Point Offset ...............................27
6. Schema Definition ..............................................28
7. Security Considerations ........................................30
8. IANA Considerations ............................................31
8.1. Relative Location Registry ................................31
8.2. URN Sub-Namespace Registration ............................33
8.3. XML Schema Registration ...................................33
8.4. Geopriv Identifiers Registry ..............................34
8.4.1. Registration of Two-Dimensional Relative
Coordinate Reference System URN ....................35
8.4.2. Registration of Three-Dimensional Relative
Coordinate Reference System URN ....................35
9. Acknowledgements ...............................................35
10. References ....................................................36
10.1. Normative References .....................................36
10.2. Informative References ...................................38
1. Introduction
This document describes a format for the expression of relative
location information.
A relative location is formed of a reference location plus a relative
offset from that reference location. The reference location can be
represented in either civic or geodetic form. The reference location
can also have dynamic components such as velocity. The relative
offset is specified in meters using a Cartesian coordinate system.
In addition to the relative location, an optional URI can be provided
to a document that contains a map, floor plan, or other spatially
oriented information. Applications could use this information to
display the relative location. Additional fields allow the map to be
oriented and scaled correctly.
Two formats are included: an XML form that is intended for use in
PIDF-LO [RFC4119] and a TLV format for use in other protocols such as
those that already convey binary representation of location
information defined in [RFC4776].
2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Overview
This document describes an extension to PIDF-LO [RFC4119] as updated
by [RFC5139] and [RFC5491], to allow the expression of a location as
an offset relative to a reference.
Reference
Location
o
\
\ Offset
\
_\|
x
Relative
Location
This extension allows the creator of a location object to include two
location values plus an offset. The two location values, named
"baseline" and "reference", combine to form the origin of the offset.
The final, relative location is described relative to this reference
point.
..--"""--..
.-' `-.
,' `.
/ Reference \
/ o \
| \ |
| \ |
| \ |
\ _\| /
`. x .' \_ Baseline
`._ Relative _.' Location
`--..___..--'
The baseline location is included outside of the <relative-location>
element. The baseline location is visible to a client that does not
understand relative location (i.e., it ignores the
<relative-location> element).
A client that does understand relative location will interpret the
location within the relative element as a refinement of the baseline
location. This document defines both a reference location, which
serves as a refinement of the baseline location and the starting
point, and an offset, which describes the location of the Target
based on this starting point.
Creators of location objects with relative location thus have a
choice of how much information to put into the baseline location and
how much to put into the reference location. For example, the
baseline location value could be precise enough to specify a building
that contains the relative location, and the reference location could
specify a point within the building from which the offset is
measured.
Location objects SHOULD NOT have all location information in the
baseline location. Doing this would cause clients that do not
understand relative location to incorrectly interpret the baseline
location (i.e., the reference point) as the actual, precise location
of the client. The baseline location is intended to carry a location
that encompasses both the reference location and the relative
location (i.e., the reference location plus offset).
It is possible to provide a valid relative location with no
information in the baseline. However, this provides recipients who
do not understand relative location with no information. A baseline
location SHOULD include sufficient information to encompass both the
reference and relative locations while providing a baseline that is
as accurate as possible.
Both the baseline and the reference location are defined as either a
geodetic location [OGC.GeoShape] or a civic address [RFC4776]. If
the baseline location was expressed as a geodetic location, the
reference MUST be geodetic. If the baseline location was expressed
as a civic address, the reference MUST be civic.
Baseline and reference locations MAY also include dynamic location
information [RFC5962].
The relative location can be expressed using a point (2- or
3-dimensional) or a shape that includes uncertainty: circle, sphere,
ellipse, ellipsoid, polygon, prism, or arc-band. Descriptions of
these shapes can be found in [RFC5491].
Optionally, a reference to a 'map' document can be provided. The
reference is a URI [RFC3986]. The document could be an image or
dataset that represents a map, floor plan, or other form. The type
of document the URI points to is described as a MIME media type
[RFC2046]. Metadata in the relative location can include the
location of the reference point in the map as well as an orientation
(angle from North) and scale to align the document Coordinate
Reference System (CRS) with the World Geodetic System 1984 (WGS84)
[WGS84] CRS. The document is assumed to be usable by the application
receiving the PIDF with the relative location to locate the reference
point in the map. This document does not describe any mechanisms for
displaying or manipulating the document other than providing the
reference location, orientation, and scale.
As an example, consider a relative location expressed as a point,
relative to a civic location:
<presence xmlns="urn:ietf:params:xml:ns:pidf"
xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"
xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
xmlns:ca="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"
xmlns:rel="urn:ietf:params:xml:ns:pidf:geopriv10:relative"
xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0"
entity="pres:relative@example.com">
<dm:device id="relative1">
<gp:geopriv>
<gp:location-info>
<ca:civicAddress xml:lang="en-AU">
<ca:country>AU</ca:country>
<ca:A1>NSW</ca:A1>
<ca:A3>Wollongong</ca:A3>
<ca:A4>North Wollongong</ca:A4>
<ca:RD>Flinders</ca:RD>
<ca:STS>Street</ca:STS>
<ca:HNO>123</ca:HNO>
</ca:civicAddress>
<rel:relative-location>
<rel:reference>
<ca:civicAddress xml:lang="en-AU">
<ca:LMK>Front Door</ca:LMK>
</ca:civicAddress>
</rel:reference>
<rel:offset>
<gml:Point xmlns:gml="http://www.opengis.net/gml"
srsName="urn:ietf:params:geopriv:relative:2d">
<gml:pos>100 50</gml:pos>
</gml:Point>
</rel:offset>
</rel:relative-location>
</gp:location-info>
<gp:usage-rules/>
<gp:method>GPS</gp:method>
<rel:map>
<rel:url type="image/png">
http://example.com/location/map.png
</rel:url>
<rel:offset>20. 120.</rel:offset>
<rel:orientation>29.</rel:orientation>
<rel:scale>20. -20.</rel:scale>
</rel:map>
</gp:geopriv>
<dm:deviceID>mac:1234567890ab</dm:deviceID>
<dm:timestamp>2007-06-22T20:57:29Z</dm:timestamp>
</dm:device>
</presence>
4. Relative Location
Relative location is a shape (e.g., point, circle, ellipse). The
shape is defined with a CRS that has a datum defined as the reference
(which appears as a civic address or geodetic location in the tuple)
and the shape coordinates as meter offsets North/East of the datum
measured in meters (with an optional Z offset relative to datum
altitude). An optional angle allows the reference CRS be to rotated
with respect to North.
4.1. Relative Coordinate System
The relative coordinate reference system uses a coordinate system
with two or three axes.
The baseline and reference locations are used to define a relative
datum. The reference location defines the origin of the coordinate
system. The centroid of the reference location is used when the
reference location contains any uncertainty.
The axes in this coordinate system are originally oriented based on
the directions of East, North, and Up from the reference location:
the first (x) axis increases to the East, the second (y) axis points
North, and the optional third (z) axis points Up. All axes of the
coordinate system use meters as a basic unit.
Any coordinates in the relative shapes use the described Cartesian
coordinate system. In the XML form, this uses a URN of
"urn:ietf:params:geopriv:relative:2d" for two-dimensional shapes and
"urn:ietf:params:geopriv:relative:3d" for three-dimensional shapes.
The binary form uses different shape type identifiers for 2D and 3D
shapes.
Dynamic location information [RFC5962] in the baseline or reference
location alters the relative coordinate system. The resulting
Cartesian coordinate system axes are rotated so that the y axis is
oriented along the direction described by the <orientation> element.
The coordinate system also moves as described by the <speed> and
<heading> elements.
The single timestamp included in the tuple (or equivalent) element
applies to all location elements, including all three components of a
relative location: baseline, reference, and relative. This is
particularly important when there are dynamic components to these
items. A location generator is responsible for ensuring the
consistency of these fields.
4.2. Placement of XML Elements
The baseline of the reference location is represented as
<location-info> like a normal PIDF-LO. Relative location adds a new
<relative-location> element to <location-info>. Within
<relative-location>, <reference> and <offset> elements are described.
Within <offset> are the shape elements described below. This
document extends PIDF-LO as described in [RFC6848].
4.3. Binary Format
This document describes a way to encode the relative location in a
binary TLV form for use in other protocols that use TLVs to represent
location.
A type-length-value encoding is used.
+------+------+------+------+------+------+------+
| Type |Length| Value ...
+------+------+------+------+------+------+------+
| T | N | Value ...
+------+------+------+------+------+------+------+
Figure 1: TLV Tuple Format
The Type field (T) is an 8-bit unsigned integer. The type codes used
are registered in an IANA-managed "Relative Location Parameters"
registry defined by this document and restricted to not include the
values defined by the "Civic Address Types (CAtypes)" registry. This
restriction permits a location reference and offset to be coded
within the same object without type collisions.
The Length field (N) is defined as an 8-bit unsigned integer. This
field can encode values from 0 to 255. The length field describes
the number of bytes in the Value. Length does not count the bytes
used for the Type or Length.
The Value field is defined separately for each type.
Each element of the relative location has a unique TLV assignment. A
relative location encoded in TLV form includes both baseline and
reference location TLVs and relative location TLVs. The reference
TLVs are followed by the relative offset and optional map TLVs
described in this document.
4.4. Distances and Angles
All distance measures used in shapes are expressed in meters.
All orientation angles used in shapes are expressed in degrees.
Orientation angles are measured from WGS84 Northing to Easting with
zero at Northing. Orientation angles in the relative coordinate
system start from the second coordinate axis (y or Northing) and
increase toward the first axis (x or Easting).
4.5. Value Encoding
The binary form uses single-precision floating-point values
[IEEE.754] to represent coordinates, distance, and angle measures.
Single-precision values are 32-bit values with a sign bit, 8 exponent
bits, and 23 fractional bits. This uses the interchange format
defined in [IEEE.754] and Section 3.6 of [RFC1014], that is: sign,
biased exponent and significand, with the most significant bit first.
Binary-encoded coordinate values are considered to be a single value
without uncertainty. When encoding a value that cannot be exactly
represented, the best approximation MUST be selected according to
[Clinger1990].
4.6. Relative Location Restrictions
More than one relative shape MUST NOT be included in either a PIDF-LO
or TLV encoding of location for a given reference point.
Any error in the reference point transfers to the location described
by the relative location. Any errors arising from an implementation
not supporting or understanding elements of the reference point
directly increases the error (or uncertainty) in the resulting
location.
4.7. Baseline TLVs
Baseline locations are described using the formats defined in
[RFC4776] or [RFC6225].
4.8. Reference TLVs
When a reference is encoded in binary form, the baseline and
reference locations are combined in a reference TLV. This TLV is
identified with the code 111 and contains civic address TLVs (if the
baseline was a civic) or geo TLVs (if the baseline was a geo).
+------+------+------+------+------+------+
| 111 |Length| Reference TLVs |
+------+------+------+------+------+------+
Figure 2: Reference TLV
4.9. Shapes
Shape data is used to represent regions of uncertainty for the
reference and relative locations. Shape data in the reference
location uses a WGS84 [WGS84] CRS. Shape data in the relative
location uses a relative CRS.
The XML form for shapes uses Geography Markup Language (GML)
[OGC.GML-3.1.1], consistent with the rules in [RFC5491]. Reference
locations use the CRS URNs specified in [RFC5491]; relative locations
use either a 2D CRS ("urn:ietf:params:geopriv:relative:2d") or a 3D
("urn:ietf:params:geopriv:relative:3d"), depending on the shape type.
The binary form of each shape uses a different shape type for 2D and
3D shapes.
Nine shape type codes are defined.
4.9.1. Point
A point "shape" describes a single point with unknown uncertainty.
It consists of a single set of coordinates.
In a two-dimensional CRS, the coordinate includes two values; in a
three-dimensional CRS, the coordinate includes three values.
4.9.1.1. XML Encoding
A point is represented in GML using the following template:
<gml:Point xmlns:gml="http://www.opengis.net/gml"
srsName="$CRS-URN$">
<gml:pos>$Coordinate-1 $Coordinate-2$ $Coordinate-3$</gml:pos>
</gml:Point>
Figure 3: GML Point Template
Where "$CRS-URN$" is replaced by a
"urn:ietf:params:geopriv:relative:2d" or
"urn:ietf:params:geopriv:relative:3d" and "$Coordinate-3$" is omitted
if the CRS is two-dimensional.
4.9.1.2. TLV Encoding
The point shape is introduced by a TLV of 113 for a 2D point and 114
for a 3D point.
+------+------+
| 113/4|Length|
+------+------+------+------+
| Coordinate-1 |
+------+------+------+------+
| Coordinate-2 |
+------+------+------+------+
| (3D-only) Coordinate-3 |
+------+------+------+------+
Figure 4: Point Encoding
4.9.2. Circle or Sphere Shape
A circle or sphere describes a single point with a single uncertainty
value in meters.
In a two-dimensional CRS, the coordinate includes two values, and the
resulting shape forms a circle. In a three-dimensional CRS, the
coordinate includes three values, and the resulting shape forms a
sphere.
4.9.2.1. XML Encoding
A circle is represented in and converted from GML using the following
template:
<gs:Circle xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0"
srsName="urn:ietf:params:geopriv:relative:2d">
<gml:pos>$Coordinate-1 $Coordinate-2$</gml:pos>
<gs:radius uom="urn:ogc:def:uom:EPSG::9001">
$Radius$
</gs:radius>
</gs:Circle>
Figure 5: GML Circle Template
A sphere is represented in and converted from GML using the following
template:
<gs:Sphere xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0"
srsName="urn:ietf:params:geopriv:relative:3d">
<gml:pos>$Coordinate-1 $Coordinate-2$ $Coordinate-3$</gml:pos>
<gs:radius uom="urn:ogc:def:uom:EPSG::9001">
$Radius$
</gs:radius>
</gs:Sphere>
Figure 6: GML Sphere Template
4.9.2.2. TLV Encoding
A circular shape is introduced by a type code of 115. A spherical
shape is introduced by a type code of 116.
+------+------+
| 115/6|Length|
+------+------+------+------+
| Coordinate-1 |
+------+------+------+------+
| Coordinate-2 |
+------+------+------+------+
| (3D-only) Coordinate-3 |
+------+------+------+------+
| Radius |
+------+------+------+------+
Figure 7: Circle or Sphere Encoding
4.9.3. Ellipse or Ellipsoid Shape
An ellipse or ellipsoid describes a point with an elliptical or
ellipsoidal uncertainty region.
In a two-dimensional CRS, the coordinate includes two values plus a
semi-major axis, a semi-minor axis, a semi-major axis orientation
(clockwise from North). In a three-dimensional CRS, the coordinate
includes three values, and in addition to the two-dimensional values,
an altitude uncertainty (semi-vertical) is added.
4.9.3.1. XML Encoding
An ellipse is represented in and converted from GML using the
following template:
<gs:Ellipse xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0"
srsName="urn:ietf:params:geopriv:relative:2d">
<gml:pos>$Coordinate-1 $Coordinate-2$</gml:pos>
<gs:semiMajorAxis uom="urn:ogc:def:uom:EPSG::9001">
$Semi-Major$
</gs:semiMajorAxis>
<gs:semiMinorAxis uom="urn:ogc:def:uom:EPSG::9001">
$Semi-Minor$
</gs:semiMinorAxis>
<gs:orientation uom="urn:ogc:def:uom:EPSG::9102">
$Orientation$
</gs:orientation>
</gs:Ellipse>
Figure 8: GML Ellipse Template
An ellipsoid is represented in and converted from GML using the
following template:
<gs:Ellipsoid xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0"
srsName="urn:ietf:params:geopriv:relative:3d">
<gml:pos>$Coordinate-1 $Coordinate-2$ $Coordinate-3$</gml:pos>
<gs:semiMajorAxis uom="urn:ogc:def:uom:EPSG::9001">
$Semi-Major$
</gs:semiMajorAxis>
<gs:semiMinorAxis uom="urn:ogc:def:uom:EPSG::9001">
$Semi-Minor$
</gs:semiMinorAxis>
<gs:verticalAxis uom="urn:ogc:def:uom:EPSG::9001">
$Semi-Vertical$
</gs:verticalAxis>
<gs:orientation uom="urn:ogc:def:uom:EPSG::9102">
$Orientation$
</gs:orientation>
</gs:Ellipsoid>
Figure 9: GML Ellipsoid Template
4.9.3.2. TLV Encoding
An ellipse is introduced by a type code of 117, and an ellipsoid is
introduced by a type code of 118.
+------+------+
| 117/8|Length|
+------+------+------+------+
| Coordinate-1 |
+------+------+------+------+
| Coordinate-2 |
+------+------+------+------+
| (3D-only) Coordinate-3 |
+------+------+------+------+------+------+------+------+
| Semi-Major Axis | Semi-Minor Axis |
+------+------+------+------+------+------+------+------+
| Orientation | (3D) Semi-Vertical Axis |
+------+------+------+------+------+------+------+------+
Figure 10: Ellipse or Ellipsoid Encoding
4.9.4. Polygon or Prism Shape
A polygon or prism includes a number of points that describe the
outer boundary of an uncertainty region. A prism also includes an
altitude for each point and prism height.
At least 3 points MUST be included in a polygon. In order to
interoperate with existing systems, an encoding SHOULD include 15 or
fewer points, unless the recipient is known to support larger
numbers.
4.9.4.1. XML Encoding
A polygon is represented in and converted from GML using the
following template:
<gml:Polygon xmlns:gml="http://www.opengis.net/gml"
srsName="urn:ietf:params:geopriv:relative:2d">
<gml:exterior>
<gml:LinearRing>
<gml:posList>
$Coordinate1-1$ $Coordinate1-2$
$Coordinate2-1$ $Coordinate2-2$
$Coordinate3-1$ ...
...
$CoordinateN-1$ $CoordinateN-2$
$Coordinate1-1$ $Coordinate1-2$
</gml:posList>
</gml:LinearRing>
</gml:exterior>
</gml:Polygon>
Figure 11: GML Polygon Template
Alternatively, a series of <pos> elements can be used in place of the
single "posList". Each <pos> element contains two or three
coordinate values.
Note that the first point is repeated at the end of the sequence of
coordinates and no explicit count of the number of points is
provided.
A GML polygon that includes altitude cannot be represented perfectly
in TLV form. When converting to the binary representation, a two-
dimensional CRS is used, and altitude is removed from each
coordinate.
A prism is represented in and converted from GML using the following
template:
<gs:Prism xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0"
srsName="urn:ietf:params:geopriv:relative:3d">
<gs:base>
<gml:Polygon>
<gml:exterior>
<gml:LinearRing>
<gml:posList>
$Coordinate1-1$ $Coordinate1-2$ $Coordinate1-3$
$Coordinate2-1$ $Coordinate2-2$ $Coordinate2-3$
$Coordinate2-1$ ... ...
...
$CoordinateN-1$ $CoordinateN-2$ $CoordinateN-3$
$Coordinate1-1$ $Coordinate1-2$ $Coordinate1-3$
</gml:posList>
</gml:LinearRing>
</gml:exterior>
</gml:Polygon>
</gs:base>
<gs:height uom="urn:ogc:def:uom:EPSG::9001">
$Height$
</gs:height>
</gs:Prism>
Figure 12: GML Prism Template
Alternatively, a series of <pos> elements can be used in place of the
single "posList". Each <pos> element contains three coordinate
values.
4.9.4.2. TLV Encoding
A polygon containing 2D points uses a type code of 119. A polygon
with 3D points uses a type code of 120. A prism uses a type code of
121. The number of points can be inferred from the length of the
TLV.
+------+------+
|119-21|Length|
+------+------+------+------+
| (3D-only) Height |
+------+------+------+------+
| Coordinate1-1 |
+------+------+------+------+
| Coordinate1-2 |
+------+------+------+------+
| (3D-only) Coordinate1-3 |
+------+------+------+------+
| Coordinate2-1 |
+------+------+------+------+
...
+------+------+------+------+
| CoordinateN-1 |
+------+------+------+------+
| CoordinateN-2 |
+------+------+------+------+
| (3D-only) CoordinateN-3 |
+------+------+------+------+
Figure 13: Polygon or Prism Encoding
Note that unlike the polygon representation in GML, the first and
last points are not the same point in the TLV representation. The
duplicated point is removed from the binary form.
4.9.5. Arc-Band Shape
An arc-band describes a region constrained by a range of angles and
distances from a predetermined point. This shape can only be
provided for a two-dimensional CRS.
Distance and angular measures are defined in meters and degrees,
respectively. Both are encoded as single-precision floating-point
values.
4.9.5.1. XML Encoding
An arc-band is represented in and converted from GML using the
following template:
<gs:ArcBand xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0"
srsName="urn:ietf:params:geopriv:relative:2d">
<gml:pos>$Coordinate-1$ $Coordinate-2$</gml:pos>
<gs:innerRadius uom="urn:ogc:def:uom:EPSG::9001">
$Inner-Radius$
</gs:innerRadius>
<gs:outerRadius uom="urn:ogc:def:uom:EPSG::9001">
$Outer-Radius$
</gs:outerRadius>
<gs:startAngle uom="urn:ogc:def:uom:EPSG::9102">
$Start-Angle$
</gs:startAngle>
<gs:openingAngle uom="urn:ogc:def:uom:EPSG::9102">
$Opening-Angle$
</gs:openingAngle>
</gs:ArcBand>
Figure 14: GML Arc-Band Template
4.9.5.2. TLV Encoding
An arc-band is introduced by a type code of 122.
+------+------+
| 122 |Length|
+------+------+------+------+
| Coordinate |
+------+------+------+------+
| Coordinate |
+------+------+------+------+------+------+------+------+
| Inner Radius | Outer Radius |
+------+------+------+------+------+------+------+------+
| Start Angle | Opening Angle |
+------+------+------+------+------+------+------+------+
Figure 15: Arc-Band Encoding
4.10. Dynamic Location TLVs
Dynamic location elements use the definitions in [RFC5962].
4.10.1. Orientation
The orientation of the Target is described using one or two angles.
Orientation uses a type code of 123.
+------+------+
| 123 |Length|
+------+------+------+------+
| Angle |
+------+------+------+------+
| (Optional) Angle |
+------+------+------+------+
Figure 16: Dynamic Orientation TLVs
4.10.2. Speed
The speed of the Target is a scalar value in meters per second.
Speed uses a type code of 124.
+------+------+
| 124 |Length|
+------+------+------+------+
| Speed |
+------+------+------+------+
Figure 17: Dynamic Speed TLVs
4.10.3. Heading
The heading, or direction of travel, is described using one or two
angles. Heading uses a type code of 125.
+------+------+
| 125 |Length|
+------+------+------+------+
| Angle |
+------+------+------+------+
| (Optional) Angle |
+------+------+------+------+
Figure 18: Dynamic Heading TLVs
4.11. Secondary Map Metadata
The optional "map" URL can be used to provide a user of relative
location with a visual reference for the location information. This
document does not describe how the recipient uses the map nor how it
locates the reference or offset within the map. Maps can be simple
images, vector files, 2D or 3D geospatial databases, or any other
form of representation understood by both the sender and recipient.
4.11.1. Map URL
In XML, the map is a <map> element defined within <relative-location>
and contains the URL. The URL is encoded as a UTF-8-encoded string.
An "http:" [RFC2616] or "https:" [RFC2818] URL MUST be used unless
the entity creating the PIDF-LO is able to ensure that authorized
recipients of this data are able to use other URI schemes. A "type"
attribute MUST be present and specifies the kind of map the URL
points to. Map types are specified as MIME media types as recorded
in the IANA Media Types registry, for example, <map type="image/png">
https://www.example.com/floorplans/123South/floor-2</map>.
In binary, the map type is a separate TLV from the map URL. The
media type uses a type code of 126; the URL uses a type code of 127.
+------+------+------+------+------+------+------+
| 126 |Length| Map Media Type ...
+------+------+------+------+------+------+------+
| 127 |Length| Map Image URL ...
+------+------+------+------+------+------+------+
Figure 19: Map URL TLVs
Note that the binary form restricts data to 255 octets. This
restriction could be problematic for URLs in particular.
Applications that use the XML form, but cannot guarantee that a
binary form won't be used, are encouraged to limit the size of the
URL to fit within this restriction.
4.11.2. Map Coordinate Reference System
The CRS used by the map depends on the type of map. For example, a
map described by a 3-D geometric model of the building may contain a
complete CRS description in it. For some kinds of maps, typically
described as images, the CRS used within the map must define the
following:
o The CRS origin
o The CRS axes used and their orientation
o The unit of measure used
This document provides elements that allow for a mapping between the
local coordinate reference system used for the relative location and
the coordinate reference system used for the map where they are not
the same.
4.11.2.1. Map Reference Point Offset
This optional element identifies the coordinates of the reference
point as it appears in the map. This value is measured in a map-
type-dependent manner, using the coordinate system of the map.
For image maps, coordinates start from the upper left corner, and
coordinates are first counted by column with positive values to the
right; then, rows are counted with positive values toward the bottom
of the image. For such an image, the first item is columns, the
second rows, and any third value applies to any third dimension used
in the image coordinate space.
The <offset> element contains 2 (or 3) coordinates similar to a GML
<pos>. For example:
<offset> 2670.0 1124.0 1022.0</offset>
The map reference point uses a type code of 129.
+------+------+
| 129 |Length|
+------+------+------+------+
| Coordinate-1 |
+------+------+------+------+
| Coordinate-2 |
+------+------+------+------+
| (3D-only) Coordinate-3 |
+------+------+------+------+
Figure 20: Map Reference Point Coordinates TLV
If omitted, a value containing all zeros is assumed. If the
coordinates provided contain fewer values than are needed, the first
value from the set is applied in place of any absent values. Thus,
if a single value is provided, that value is used for Coordinate-2
and Coordinate-3 (if required). If two values are provided and three
are required, the value of Coordinate-1 is used in place of
Coordinate-3.
4.11.2.2. Map Orientation
The map orientation includes the orientation of the map direction in
relation to the Earth. Map orientation is expressed relative to the
orientation of the relative coordinate system. This means that map
orientation with respect to WGS84 North is the sum of the orientation
field and any orientation included in a dynamic portion of the
reference location. Both values default to zero if no value is
specified.
This type uses a single-precision floating-point value of degrees
relative to North.
In XML, the <orientation> element contains a single floating-point
value, for example, <orientation>67.00</orientation>. In TLV form,
map orientation uses the code 130:
+------+------+------+------+------+------+
| 130 |Length| Angle |
+------+------+------+------+------+------+
Figure 21: Map Orientation TLV
4.11.2.3. Map Scale
The optional map scale describes the relationship between the units
of measure used in the map, relative to the meters unit used in the
relative coordinate system.
This type uses a sequence of IEEE 754 [IEEE.754] single-precision
floating-point values to represent scale as a sequence of numeric
values. The units of these values are dependent on the type of map
and could, for example, be pixels per meter for an image.
A scaling factor is provided for each axis in the coordinate system.
For a two-dimensional coordinate system, two values are included to
allow for different scaling along the x and y axes independently.
For a three-dimensional coordinate system, three values are specified
for the x, y, and z axes. Decoders can determine the number of
scaling factors by examining the length field.
Alternatively, a single scaling value MAY be used to apply the same
scaling factor to all coordinate components.
Images that use a rows/columns coordinate system often use a left-
handed coordinate system. A negative value for the y/rows axis
scaling value can be used to account for any change in direction
between the y axis used in the relative coordinate system and the
rows axis of the image coordinate system.
In XML, the <scale> element MAY contain a single scale value or MAY
contain 2 (or 3) values in XML list form. In TLV form, scale uses a
type code of 131. The length of the TLV determines how many scale
values are present:
+------+------+------+------+------+------+
| 131 |Length| Scale(s) ...
+------+------+------+------+------+------+
Figure 22: Map Scale TLV
4.11.3. Map Example
An example of expressing a map is:
<rel:map>
<rel:url type="image/jpeg">
http://example.com/map.jpg
</rel:url>
<rel:offset>200 210</rel:offset>
<rel:orientation>68</rel:orientation>
<rel:scale>2.90 -2.90</rel:scale>
</rel:map>
Figure 23: Map Example
5. Examples
The examples in this section combine elements from [RFC3863],
[RFC4119], [RFC4479], [RFC5139], and [OGC.GeoShape].
5.1. Civic PIDF with Polygon Offset
<presence xmlns="urn:ietf:params:xml:ns:pidf"
xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"
xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
xmlns:ca="urn:ietf:params:xml:ns:pidf:geopriv10:civicAddr"
xmlns:rel="urn:ietf:params:xml:ns:pidf:geopriv10:relative"
xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0"
entity="pres:ness@example.com">
<dm:device id="nesspc-1">
<gp:geopriv>
<gp:location-info>
<ca:civicAddress xml:lang="en-AU">
<ca:country>AU</ca:country>
<ca:A1>NSW</ca:A1>
<ca:A3>Wollongong</ca:A3>
<ca:A4>North Wollongong</ca:A4>
<ca:RD>Flinders</ca:RD>
<ca:STS>Street</ca:STS>
<ca:HNO>123</ca:HNO>
</ca:civicAddress>
<rel:relative-location>
<rel:reference>
<ca:civicAddress xml:lang="en-AU">
<ca:LMK>Front Door</ca:LMK>
<ca:BLD>A</ca:BLD>
<ca:FLR>I</ca:FLR>
<ca:ROOM>113</ca:ROOM>
</ca:civicAddress>
</rel:reference>
<rel:offset>
<gml:Polygon xmlns:gml="http://www.opengis.net/gml"
srsName="urn:ietf:params:geopriv:relative:2d">
<gml:exterior>
<gml:LinearRing>
<gml:pos>433.0 -734.0</gml:pos> <!--A-->
<gml:pos>431.0 -733.0</gml:pos> <!--F-->
<gml:pos>431.0 -732.0</gml:pos> <!--E-->
<gml:pos>433.0 -731.0</gml:pos> <!--D-->
<gml:pos>434.0 -732.0</gml:pos> <!--C-->
<gml:pos>434.0 -733.0</gml:pos> <!--B-->
<gml:pos>433.0 -734.0</gml:pos> <!--A-->
</gml:LinearRing>
</gml:exterior>
</gml:Polygon>
</rel:offset>
</rel:relative-location>
</gp:location-info>
<gp:usage-rules/>
<gp:method>GPS</gp:method>
</gp:geopriv>
<dm:deviceID>mac:1234567890ab</dm:deviceID>
<dm:timestamp>2007-06-22T20:57:29Z</dm:timestamp>
</dm:device>
</presence>
5.2. Geo PIDF with Circle Offset
<?xml version="1.0" encoding="UTF-8"?>
<presence xmlns="urn:ietf:params:xml:ns:pidf"
xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model"
xmlns:gp="urn:ietf:params:xml:ns:pidf:geopriv10"
xmlns:rel="urn:ietf:params:xml:ns:pidf:geopriv10:relative"
xmlns:gml="http://www.opengis.net/gml"
xmlns:gs="http://www.opengis.net/pidflo/1.0"
entity="pres:point2d@example.com">
<dm:device id="point2d">
<gp:geopriv>
<gp:location-info>
<gs:Circle srsName="urn:ogc:def:crs:EPSG::4326">
<gml:pos>-34.407 150.883</gml:pos>
<gs:radius uom="urn:ogc:def:uom:EPSG::9001">
50.0
</gs:radius>
</gs:Circle>
<rel:relative-location>
<rel:reference>
<gml:Point srsName="urn:ogc:def:crs:EPSG::4326">
<gml:pos>-34.407 150.883</gml:pos>
</gml:Point>
</rel:reference>
<rel:offset>
<gs:Circle xmlns:gml="http://www.opengis.net/gml"
srsName="urn:ietf:params:geopriv:relative:2d">
<gml:pos>500.0 750.0</gml:pos>
<gs:radius uom="urn:ogc:def:uom:EPSG::9001">
5.0
</gs:radius>
</gs:Circle>
</rel:offset>
<rel:map>
<rel:url type="image/png">
https://www.example.com/flrpln/123South/flr-2
</rel:url>
<rel:offset>2670.0 1124.0 1022.0</rel:offset>
<rel:orientation>67.00</rel:orientation>
<rel:scale>10 -10</rel:scale>
</rel:map>
</rel:relative-location>
</gp:location-info>
<gp:usage-rules/>
<gp:method>Wiremap</gp:method>
</gp:geopriv>
<dm:deviceID>mac:1234567890ab</dm:deviceID>
<dm:timestamp>2007-06-22T20:57:29Z</dm:timestamp>
</dm:device>
</presence>
5.3. Civic TLV with Point Offset
+--------+-------------------------------------------------+
| Type | Value |
+--------+-------------------------------------------------+
| 0 | en |
| | |
| 1 | IL |
| | |
| 3 | Chicago |
| | |
| 34 | Wacker |
| | |
| 18 | Drive |
| | |
| 19 | 3400 |
| | |
| 112 | Reference |
| | |
| 25 | Building A |
| | |
| 27 | Floor 6 |
| | |
| 26 | Suite 213 |
| | |
| 28 | Reception Area |
| | |
| 115 | 100 70 |
| | |
| 126 | image/png |
| | |
| 127 | http://maps.example.com/3400Wacker/A6 |
| | |
| 129 | 0.0 4120.0 |
| | |
| 130 | 113.0 |
| | |
| 131 | 10.6 |
+--------+-------------------------------------------------+
6. Schema Definition
Note: The pattern value for "mimeType" has been folded onto
multiple lines. Whitespace has been added to conform to comply
with document formatting restrictions. Extra whitespace around
the line endings MUST be removed before using this schema.
<?xml version="1.0"?>
<xs:schema
xmlns:rel="urn:ietf:params:xml:ns:pidf:geopriv10:relative"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:gml="http://www.opengis.net/gml"
targetNamespace="urn:ietf:params:xml:ns:pidf:geopriv10:relative"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<xs:annotation>
<xs:appinfo
source="urn:ietf:params:xml:schema:pidf:geopriv10:relative">
Relative Location for PIDF-LO
</xs:appinfo>
<xs:documentation source="http://ietf.org/rfc/rfc7035.txt">
This schema defines a location representation that allows for
the description of locations that are relative to another.
An optional map reference is also defined.
</xs:documentation>
</xs:annotation>
<xs:import namespace="http://www.opengis.net/gml"/>
<xs:element name="relative-location" type="rel:relativeType"/>
<xs:complexType name="relativeType">
<xs:complexContent>
<xs:restriction base="xs:anyType">
<xs:sequence>
<xs:element name="reference" type="rel:referenceType"/>
<xs:element name="offset" type="rel:offsetType"/>
<xs:any namespace="##any" processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:anyAttribute namespace="##other" processContents="lax"/>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="referenceType">
<xs:complexContent>
<xs:restriction base="xs:anyType">
<xs:sequence>
<xs:any namespace="##other" processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="offsetType">
<xs:complexContent>
<xs:restriction base="xs:anyType">
<xs:sequence>
<xs:element ref="gml:_Geometry"/>
<xs:any namespace="##other" processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
<xs:element name="map" type="rel:mapType"/>
<xs:complexType name="mapType">
<xs:complexContent>
<xs:restriction base="xs:anyType">
<xs:sequence>
<xs:element name="url" type="rel:mapUrlType"/>
<xs:element name="offset" type="rel:doubleList"
minOccurs="0"/>
<xs:element name="orientation" type="rel:doubleList"
minOccurs="0"/>
<xs:element name="scale" type="rel:doubleList"
minOccurs="0"/>
</xs:sequence>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="mapUrlType">
<xs:simpleContent>
<xs:extension base="xs:anyURI">
<xs:attribute name="type" type="rel:mimeType"
default="application/octet-stream"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:simpleType name="mimeType">
<xs:restriction base="xs:token">
<xs:pattern value="[!#$%&'\*\+\-\.\dA-Z^_`a-z\|~]+
/[!#$%&'\*\+\-\.\dA-Z^_`a-z\|~]+([\t ]*;([\t ])*[!#$%&
'\*\+\-\.\dA-Z^_`a-z\|~]+=([!#$%&'\*\+\-\.\dA-Z^_`a-z\|~]+|
"([!#-\[\]-~]|[\t ]*|\\[\t !-~])*"))*"/>
</xs:restriction>
</xs:simpleType>
<xs:simpleType name="doubleList">
<xs:list itemType="xs:double"/>
</xs:simpleType>
</xs:schema>
7. Security Considerations
This document describes a data format. To a large extent, security
properties of this depend on how this data is used.
Privacy for location data is typically important. Adding relative
location may increase the precision of the location but does not
otherwise alter its privacy considerations, which are discussed in
[RFC4119].
The map URL provided in a relative location could accidentally reveal
information if a Location Recipient uses the URL to acquire the map.
The coverage area of a map, or parameters of the URL itself, could
provide information about the location of a Target. In combination
with other information that could reveal the set of potential Targets
that the Location Recipient has location information for, acquiring a
map could leak significant information. In particular, it is
important to note that the Target and Location Recipient are often
the same entity.
Access to map URLs MUST be secured with TLS [RFC5246] (that is,
restricting the map URL to be an https URI), unless the map URL
cannot leak information about the Target's location. This restricts
information about the map URL to the entity serving the map request.
If the map URL conveys more information about a Target than a map
server is authorized to receive, that URL MUST NOT be included in the
PIDF-LO.
8. IANA Considerations
8.1. Relative Location Registry
This document creates a new registry called "Relative Location
Parameters". This shares a page, titled "Civic Address Types
Registry" with the existing "Civic Address Types (CAtypes)" registry.
As defined in [RFC5226], this new registry operates under "IETF
Review" rules.
The content of this registry includes:
Relative Location Code (RLtype): Numeric identifier, assigned by
IANA.
Brief description: Short description identifying the meaning of the
element.
Reference to published specification: A stable reference to an RFC
that describes the value in sufficient detail so that
interoperability between independent implementations is possible.
Values requested to be assigned into this registry MUST NOT conflict
with values assigned in the "Civic Address Types (CAtypes)" registry
or vice versa, unless the IANA Considerations section for the new
value explicitly overrides this prohibition and the document defining
the value describes how conflicting TLV codes will be interpreted by
implementations. To ensure this, the CAtypes entries are explicitly
reserved in the initial values table below. Those reserved entries
can be changed, but only with caution, as explained here.
To make this clear for future users of the registry, the following
note is added to the "Civic Address Types (CAtypes)" registry:
The registration of new values should be accompanied by a
corresponding reservation in the Relative Location Parameters
registry.
Similarly, the "Relative Location Parameters" registry bears the
note:
The registration of new values should be accompanied by a
corresponding reservation in the Civic Address Types (CAtypes)
registry.
The values defined are:
+--------+----------------------------------------+-----------+
| RLtype | description | Reference |
+--------+----------------------------------------+-----------+
| 0-40 | RESERVED by CAtypes registry | RFC 7035 &|
| 128 | | RFC 4776 |
+--------+----------------------------------------+-----------+
| 111 | relative location reference | RFC 7035 |
| 113 | relative location shape 2D point | RFC 7035 |
| 114 | relative location shape 3D point | RFC 7035 |
| 115 | relative location shape circular | RFC 7035 |
| 116 | relative location shape spherical | RFC 7035 |
| 117 | relative location shape elliptical | RFC 7035 |
| 118 | relative location shape ellipsoid | RFC 7035 |
| 119 | relative location shape 2D polygon | RFC 7035 |
| 120 | relative location shape 3D polygon | RFC 7035 |
| 121 | relative location shape prism | RFC 7035 |
| 122 | relative location shape arc-band | RFC 7035 |
| 123 | relative location dynamic orientation | RFC 7035 |
| 124 | relative location dynamic speed | RFC 7035 |
| 125 | relative location dynamic heading | RFC 7035 |
| 126 | relative location map type | RFC 7035 |
| 127 | relative location map URI | RFC 7035 |
| 129 | relative location map coordinates | RFC 7035 |
| 130 | relative location map angle | RFC 7035 |
| 131 | relative location map scale | RFC 7035 |
+--------+----------------------------------------+-----------+
8.2. URN Sub-Namespace Registration
This document registers a new XML namespace, as per the guidelines in
[RFC3688].
URI: urn:ietf:params:xml:ns:pidf:geopriv10:relative
Registrant Contact: IETF, GEOPRIV working group (geopriv@ietf.org),
Martin Thomson (martin.thomson@skype.net).
XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<title>GEOPRIV Relative Location</title>
</head>
<body>
<h1>Format for representing relative location</h1>
<h2>urn:ietf:params:xml:ns:pidf:geopriv10:relative</h2>
<p>See <a href="http://www.rfc-editor.org/rfc/rfc7035.txt">
RFC 7035</a>.</p>
</body>
</html>
END
8.3. XML Schema Registration
This section registers an XML schema as per the procedures in
[RFC3688].
URI: urn:ietf:params:xml:schema:pidf:geopriv10:relative
Registrant Contact: IETF, GEOPRIV working group (geopriv@ietf.org),
Martin Thomson (martin.thomson@skype.net)
Schema: The XML for this schema is found in Section 6 of this
document.
8.4. Geopriv Identifiers Registry
This section registers two URNs for use in identifying relative
coordinate reference systems. These are added to a new "Geopriv
Identifiers" registry according to the procedures in Section 4 of
[RFC3553]. The "Geopriv Identifiers" registry is entered under the
"Uniform Resource Name (URN) Namespace for IETF Use" category.
Registrations in this registry follow the "IETF Review" [RFC5226]
policy.
Registry name: Geopriv Identifiers
URN Prefix: urn:ietf:params:geopriv:
Specification: RFC 7035 (this document)
Repository: http://www.iana.org/assignments/geopriv-identifiers
Index value: Values in this registry are URNs or URN prefixes that
start with the prefix "urn:ietf:params:geopriv:". Each is
registered independently.
Each registration in the "Geopriv Identifiers" registry requires the
following information:
URN: The complete URN that is used or the prefix for that URN.
Description: A summary description for the URN or URN prefix.
Specification: A reference to a specification describing the URN or
URN prefix.
Contact: Email for the person or groups making the registration.
Index value: As described in [RFC3553], URN prefixes that are
registered include a description of how the URN is constructed.
This is not applicable for specific URNs.
The "Geopriv Identifiers" registry has two initial registrations,
included in the following sections.
8.4.1. Registration of Two-Dimensional Relative Coordinate Reference
System URN
This section registers the "urn:ietf:params:geopriv:relative:2d" URN
in the "Geopriv Identifiers" registry.
URN: urn:ietf:params:geopriv:relative:2d
Description: A two-dimensional relative coordinate reference system
Specification: RFC 7035 (this document)
Contact: IETF, GEOPRIV working group (geopriv@ietf.org), Martin
Thomson (martin.thomson@skype.net)
Index value: N/A
8.4.2. Registration of Three-Dimensional Relative Coordinate Reference
System URN
This section registers the "urn:ietf:params:geopriv:relative:3d" URN
in the "Geopriv Identifiers" registry.
URN: urn:ietf:params:geopriv:relative:3d
Description: A three-dimensional relative coordinate reference
system
Specification: RFC 7035 (this document)
Contact: IETF, GEOPRIV working group (geopriv@ietf.org), Martin
Thomson (martin.thomson@skype.net)
Index value: N/A
9. Acknowledgements
This document is the product of a design team on relative location.
Besides the authors, this team included Marc Linsner, James Polk, and
James Winterbottom.
10. References
10.1. Normative References
[Clinger1990]
Clinger, W., "How to Read Floating Point Numbers
Accurately", Proceedings of Conference on Programming
Language Design and Implementation, pp. 92-101, 1990.
[IEEE.754] IEEE, "IEEE Standard for Floating-Point Arithmetic", IEEE
Standard 754-2008, August 2008.
[OGC.GML-3.1.1]
Cox, S., Daisey, P., Lake, R., Portele, C., and A.
Whiteside, "Geographic information - Geography Markup
Language (GML)", OpenGIS 03-105r1, April 2004,
<http://portal.opengeospatial.org/files/
?artifact_id=4700>.
[OGC.GeoShape]
Thomson, M. and C. Reed, "GML 3.1.1 PIDF-LO Shape
Application Schema for use by the Internet Engineering
Task Force (IETF)", OGC Best Practice 06-142r1, Version:
1.0, April 2007.
[RFC1014] Sun Microsystems, Inc., "XDR: External Data Representation
standard", RFC 1014, June 1987.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
November 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An
IETF URN Sub-namespace for Registered Protocol
Parameters", BCP 73, RFC 3553, June 2003.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC
3986, January 2005.
[RFC4119] Peterson, J., "A Presence-based GEOPRIV Location Object
Format", RFC 4119, December 2005.
[RFC4776] Schulzrinne, H., "Dynamic Host Configuration Protocol
(DHCPv4 and DHCPv6) Option for Civic Addresses
Configuration Information", RFC 4776, November 2006.
[RFC5139] Thomson, M. and J. Winterbottom, "Revised Civic Location
Format for Presence Information Data Format Location
Object (PIDF-LO)", RFC 5139, February 2008.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5491] Winterbottom, J., Thomson, M., and H. Tschofenig, "GEOPRIV
Presence Information Data Format Location Object (PIDF-LO)
Usage Clarification, Considerations, and Recommendations",
RFC 5491, March 2009.
[RFC5962] Schulzrinne, H., Singh, V., Tschofenig, H., and M.
Thomson, "Dynamic Extensions to the Presence Information
Data Format Location Object (PIDF-LO)", RFC 5962,
September 2010.
[RFC6225] Polk, J., Linsner, M., Thomson, M., and B. Aboba, "Dynamic
Host Configuration Protocol Options for Coordinate-Based
Location Configuration Information", RFC 6225, July 2011.
[RFC6848] Winterbottom, J., Thomson, M., Barnes, R., Rosen, B., and
R. George, "Specifying Civic Address Extensions in the
Presence Information Data Format Location Object (PIDF-
LO)", RFC 6848, January 2013.
[WGS84] US National Imagery and Mapping Agency, "Department of
Defense (DoD) World Geodetic System 1984 (WGS 84), Third
Edition", NIMA TR8350.2, January 2000.
10.2. Informative References
[RFC3863] Sugano, H., Fujimoto, S., Klyne, G., Bateman, A., Carr,
W., and J. Peterson, "Presence Information Data Format
(PIDF)", RFC 3863, August 2004.
[RFC4479] Rosenberg, J., "A Data Model for Presence", RFC 4479, July
2006.
Authors' Addresses
Martin Thomson
Microsoft
3210 Porter Drive
Palo Alto, CA 94304
US
Phone: +1 650-353-1925
EMail: martin.thomson@skype.net
Brian Rosen
Neustar
470 Conrad Dr
Mars, PA 16046
US
EMail: br@brianrosen.net
Dorothy Stanley
Aruba Networks
1322 Crossman Ave
Sunnyvale, CA 94089
US
EMail: dstanley@arubanetworks.com
Gabor Bajko
Nokia
323 Fairchild Drive
Mountain View, CA 94043
US
EMail: gabor.bajko@nokia.com
Allan Thomson
Lookingglass Cyber Solutions
1001 S Kenwood Avenue
Baltimore, MD 21224
US
EMail: athomson@lgscout.com