GEOPRIV Presence Information Data Format Location Object (PIDF-LO) Usage Clarification, Considerations, and Recommendations
RFC 5491

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Network Working Group                                    J. Winterbottom
Request for Comments: 5491                                    M. Thomson
Updates: 4119                                         Andrew Corporation
Category: Standards Track                                  H. Tschofenig
                                                  Nokia Siemens Networks
                                                              March 2009

   GEOPRIV Presence Information Data Format Location Object (PIDF-LO)
        Usage Clarification, Considerations, and Recommendations

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (c) 2009 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 in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

Winterbottom, et al.        Standards Track                     [Page 1]
RFC 5491                 GEOPRIV PIDF-LO Usage                March 2009

Abstract

   The Presence Information Data Format Location Object (PIDF-LO)
   specification provides a flexible and versatile means to represent
   location information.  There are, however, circumstances that arise
   when information needs to be constrained in how it is represented.
   In these circumstances, the range of options that need to be
   implemented are reduced.  There is growing interest in being able to
   use location information contained in a PIDF-LO for routing
   applications.  To allow successful interoperability between
   applications, location information needs to be normative and more
   tightly constrained than is currently specified in RFC 4119 (PIDF-
   LO).  This document makes recommendations on how to constrain,
   represent, and interpret locations in a PIDF-LO.  It further
   recommends a subset of Geography Markup Language (GML) 3.1.1 that is
   mandatory to implement by applications involved in location-based
   routing.

Table of Contents

   1. Introduction ....................................................3
   2. Terminology .....................................................3
   3. Using Location Information ......................................4
      3.1. Single Civic Location Information ..........................7
      3.2. Civic and Geospatial Location Information ..................7
      3.3. Manual/Automatic Configuration of Location Information .....8
      3.4. Multiple Location Objects in a Single PIDF-LO ..............9
   4. Geodetic Coordinate Representation .............................10
   5. Geodetic Shape Representation ..................................10
      5.1. Polygon Restrictions ......................................12
      5.2. Shape Examples ............................................13
           5.2.1. Point ..............................................13
           5.2.2. Polygon ............................................14
           5.2.3. Circle .............................................17
           5.2.4. Ellipse ............................................17
           5.2.5. Arc Band ...........................................19
           5.2.6. Sphere .............................................21
           5.2.7. Ellipsoid ..........................................22
           5.2.8. Prism ..............................................24
   6. Security Considerations ........................................26
   7. Acknowledgments ................................................26
   8. References .....................................................26
      8.1. Normative References ......................................26
      8.2. Informative References ....................................27

Winterbottom, et al.        Standards Track                     [Page 2]
RFC 5491                 GEOPRIV PIDF-LO Usage                March 2009

1.  Introduction

   The Presence Information Data Format Location Object (PIDF-LO)
   [RFC4119] is the recommended way of encoding location information and
   associated privacy policies.  Location information in a PIDF-LO may
   be described in a geospatial manner based on a subset of Geography
   Markup Language (GML) 3.1.1 [OGC-GML3.1.1] or as civic location
   information [RFC5139].  A GML profile for expressing geodetic shapes
   in a PIDF-LO is described in [GeoShape].  Uses for the PIDF-LO are
   envisioned in the context of numerous location-based applications.