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Versions: (draft-schulzrinne-geopriv-dhcp-civil) 00 01 02 03 04 05 06 07 08 09 RFC 4676

GEOPRIV                                                   H. Schulzrinne
Internet-Draft                                               Columbia U.
Expires: March 29, 2005                               September 28, 2004


   Dynamic Host Configuration Protocol (DHCPv4 and DHCPv6) Option for
               Civic Addresses Configuration Information
                    draft-ietf-geopriv-dhcp-civil-04

Status of this Memo

   This document is an Internet-Draft and is subject to all provisions
   of section 3 of RFC 3667.  By submitting this Internet-Draft, each
   author represents that any applicable patent or other IPR claims of
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   which he or she become aware will be disclosed, in accordance with
   RFC 3668.

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   This Internet-Draft will expire on March 29, 2005.

Copyright Notice

   Copyright (C) The Internet Society (2004).

Abstract

   This document specifies a Dynamic Host Configuration Protocol (DHCPv4
   and DHCPv6) option for the civic location of the client or the DHCP
   server.  The Location Configuration Information (LCI) includes
   information about the country, administrative units such as states,
   provinces and cities, as well as street addresses and building
   information.




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Table of Contents

   1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Format of the DHCP Civic Location Option . . . . . . . . . . .  6
     3.1   Overall Format for DHCPv4  . . . . . . . . . . . . . . . .  6
     3.2   Overall Format for DHCPv6  . . . . . . . . . . . . . . . .  6
     3.3   Element Format . . . . . . . . . . . . . . . . . . . . . .  7
     3.4   Civic Address Components . . . . . . . . . . . . . . . . .  7
   4.  Example  . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
   7.1   Normative References . . . . . . . . . . . . . . . . . . . . 15
   7.2   Informative References . . . . . . . . . . . . . . . . . . . 15
       Author's Address . . . . . . . . . . . . . . . . . . . . . . . 16
   A.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 17
       Intellectual Property and Copyright Statements . . . . . . . . 18

































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1.  Terminology

   In this document, the key words "MUST", "MUSTNOT", "REQUIRED",
   "SHALL", "SHALLNOT", "SHOULD", "SHOULDNOT", "RECOMMENDED", "MAY", and
   "OPTIONAL" are to be interpreted as described in RFC 2119 [1] and
   indicate requirement levels for compliant implementations.













































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2.  Introduction

   Many end system services can benefit by knowing the approximate
   location of the end device.  In particular, IP telephony devices need
   to know their location to contact the appropriate emergency response
   agency and to be found by emergency responders.

   There are two common ways to identify the location of an object,
   either through geospatial coordinates or by so-called civic address.
   Geospatial coordinates indicate longitude, latitude and altitude,
   while civic addresses indicate a street address.

   A related document [13] describes a DHCPv4 [2] option for conveying
   geospatial information to a device.  This draft describes how DHCPv4
   and DHCPv6 [5] can be used to convey the civic location to devices.
   Both can be used simultaneously, increasing the chance to deliver
   accurate and timely location information to emergency responders.

   End systems that obtain location information via the mechanism
   described here then use other protocol mechanisms to communicate this
   information to the emergency call center or to convey it as part of
   presence information.

   Civic information is useful since it often provides additional,
   human-usable information particularly within buildings.  Also,
   compared to geospatial information, it is readily obtained for most
   occupied structures and can often be interpreted even if incomplete.
   For example, for many large university or corporate campuses,
   geocoding information to building and room granularity may not be
   readily available.

   Unlike geospatial information, the format for civic information
   differs from country to country.  Thus, this draft establishes an
   IANA registry for civic location data fields.  The initial set of
   data fields is derived from standards published by the United States
   National Emergency Number Association (NENA) [16].  It is anticipated
   that other countries can reuse many of the data elements.

   The same civic address information can often be rendered in multiple
   languages and scripts.  For example, Korean addresses are often shown
   in Hangul, Latin and Kanji, while some older cities have multiple
   language variants (Munich, Muenchen and Monaco, for example).  Since
   DHCPv4 and DHCPv6 do not currently support a mechanism to query for a
   specific script or language, the DHCP server SHOULD provide all
   common renderings to the client and MUST provide at least the
   rendering in the language and script appropriate to the location
   indicated.  For example, for use in presence information, the target
   may be visiting from a foreign country and want to convey the



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   information in a format suitable for watchers in its home country.
   For emergency services, the rendering in the local language is likely
   to be most appropriate.  To provide multiple renderings, the client
   repeats sequences of address elements, prefixing each with 'language'
   and/or 'script' element (see Section 3.3).  The language and script
   remain in effect for subsequent elements until overridden by another
   language or script element.

   The DHCP server MAY provide location information for multiple
   locations related to the target, for example, both the network
   element and the network jack itself.  This is likely to help in
   debugging network problems, for example.

   As discussed in Security Considerations (Section 5), the GeoConf_Civi
   option SHOULD be returned by DHCP servers only when the DHCP client
   has included this option in its 'parameter request list' (Section 3.5
   [2]).

   The DHCP long-options mechanism described in RFC 3396 [8] MUST be
   used if the civic address option exceeds the maximum DHCP option size
   of 255 octets.






























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3.  Format of the DHCP Civic Location Option

3.1  Overall Format for DHCPv4

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | GEOCONF_CIVIC |       N       |          Countrycode          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    What       |        civic address elements                ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Code GEOCONF_CIVIC: The code for this DHCP option is TBD by IANA.
   N: The length of this option is variable.
   Countrycode: The two-letter ISO 3166 country code in capital ASCII
      letters, e.g., DE or US.
   What: The 'what' element describes which location the DHCP refers to.
      Currently, three options are defined:  the location of the DHCP
      server (a value of 0), the location of the network element
      believed to be closest to the client (a value of 1) or the
      location of the client (a value of 2).  Option (2) SHOULD be used,
      but may not be known.  Options (0) and (1) SHOULD NOT be used
      unless it is known that the DHCP client is in close physical
      proximity to the server or network element.

   Civic address element: Zero or more elements comprising the civic
      address, with the format described below (Section 3.3).

3.2  Overall Format for DHCPv6

   The DHCPv6 [5] civic address option refers generally to the client as
   a whole.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      OPTION_CIVIC_ADDRESS     |         option-len            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Countrycode           |   what        |  elements    ...
   |                     civic address elements                    |
   |                              ...                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   option-code: OPTION_CIVIC_ADDRESS (TBD)
   option-len: Length of the Countrycode, 'what' and civic address
      elements.





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   Countrycode: See above (Section 3.1).
   What: See above (Section 3.1).
   Civic address element: See above (Section 3.1).

3.3  Element Format

   For both DHCPv4 and DHCPv6, each civic address element has the
   following format:

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   CAtype      |   CAlength    |      CAvalue                 ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   CAtype: A one-octet descriptor of the data civic address value.
   CAlength: The length, in octets, of the CAvalue, not including the
      CAlength field itself.  Data SHOULD be encoded in mixed case,
      following the customary spelling.
   CAvalue: The civic address value, encoded as UTF-8 [6], and written
      in uppercase letters where applicable.  The script indication is
      written in mixed-case, with the first letter a capital letter.

   Elements SHOULD be included in numeric order from lowest to highest
   of their CAtype if the server only provides one language and script
   rendition.  In general, an element is labeled in its language and
   script by the most recent 'language tag' (CAtype = 0) element
   preceding it.  Since not all elements depend on the script and
   language, a client accumulates the elements by CAtype and then
   selects the most desirable language and script rendition if there are
   multiple elements for the same CAtype.

3.4  Civic Address Components

   Since each country has different administrative hierarchies, with
   often the same (English) names, this specification adopts a simple
   hierarchical notation that is then instantiated for each country.  We
   assume that five levels are sufficient for sub-national divisions
   above the street level.

   All elements are OPTIONAL and can appear in any order.  Abbreviations
   do not need a trailing period.  It is RECOMMENDED that all elements
   in a particular script (CAtype 128) and language (CAtype 0) be
   grouped together as that reduces the number of script and language
   identifiers needed.






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   +----------------------+----------------------+---------------------+
   | CAtype               | label                | description         |
   +----------------------+----------------------+---------------------+
   | 1                    | A1                   | national            |
   |                      |                      | subdivisions        |
   |                      |                      | (state, region,     |
   |                      |                      | province,           |
   |                      |                      | prefecture)         |
   |                      |                      |                     |
   | 2                    | A2                   | county, parish, gun |
   |                      |                      | (JP), district (IN) |
   |                      |                      |                     |
   | 3                    | A3                   | city, township, shi |
   |                      |                      | (JP)                |
   |                      |                      |                     |
   | 4                    | A4                   | city division,      |
   |                      |                      | borough, city       |
   |                      |                      | district, ward,     |
   |                      |                      | chou (JP)           |
   |                      |                      |                     |
   | 5                    | A5                   | neighborhood, block |
   |                      |                      |                     |
   | 6                    | A6                   | street              |
   +----------------------+----------------------+---------------------+

                                Table 1

   For specific countries, the administrative sub-divisions are
   described below.

   CA (Canada): The mapping to NENA designations is shown in
      parentheses.  A1=province (STA); A2=county (CNA); A3=city or town
      (MCN); A6=street (STN).
   DE (Germany): A1=state (Bundesstaat); A2=county (Regierungsbezirk);
      A3=city (Stadt, Gemeinde); A6=street (Strasse).  Street suffixes
      (STS) are used only for designations that are a separate word
      (e.g., Marienthaler Strasse).
   JP (Japan): A1=metropolis (To, Fu) or prefecture (Ken, Do); A2=city
      (Shi) or rural area (Gun); A3=ward (Ku) or village (Mura); A4=town
      (Chou or Machi); A5=city district (Choume); A6=block (Banchi or
      Ban).
   KR (Korea): A1=province (Do); A2=county (gun); A3=city or village
      (ri); A4=urban district (gu); A5=neighborhood (dong); A6=street
      (no, ro, ga or gil).
   US (United States): The mapping to NENA designations is shown in
      parentheses.  A1=state (STA), using the the two-letter state and
      possession abbreviations recommended by the United States Postal
      Service Publication 28 [15], Appendix B; A2=county (CNA); A3=civic



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      community name (city or town) (MCN); A6=street (STN).  A4 and A5
      are not used.  The civic community name (MCN) reflects the
      political boundaries.  These may differ from postal delivery
      assignments for historical or practical reasons.

   Additional CA types appear in many countries and are simply omitted
   where they are not needed or known:

   +------------+------------+-------------+-------------+-------------+
   | CAtype     | NENA       | PIDF        | Description | Examples    |
   +------------+------------+-------------+-------------+-------------+
   | 0          |            |             | language    | i-default   |
   |            |            |             |             | [3]         |
   |            |            |             |             |             |
   | 16         | PRD        | PRD         | leading     | N           |
   |            |            |             | street      |             |
   |            |            |             | direction   |             |
   |            |            |             |             |             |
   | 17         | POD        | POD         | trailing    | SW          |
   |            |            |             | street      |             |
   |            |            |             | suffix      |             |
   |            |            |             |             |             |
   | 18         | STS        | STS         | street      | AVE, PLATZ  |
   |            |            |             | suffix      |             |
   |            |            |             |             |             |
   | 19         | HNO        | HNO         | house       | 123         |
   |            |            |             | number      |             |
   |            |            |             |             |             |
   | 20         | HNS        | HNS         | house       | A, 1/2      |
   |            |            |             | number      |             |
   |            |            |             | suffix      |             |
   |            |            |             |             |             |
   | 21         | LMK        | LMK         | landmark or | COLUMBIA    |
   |            |            |             | vanity      | UNIVERSITY  |
   |            |            |             | address     |             |
   |            |            |             |             |             |
   | 22         | LOC        | LOC         | additional  | SOUTH WING  |
   |            |            |             | location    |             |
   |            |            |             | information |             |
   |            |            |             |             |             |
   | 23         | NAM        | NAM         | name        | JOE'S       |
   |            |            |             | (residence  | BARBERSHOP  |
   |            |            |             | and office  |             |
   |            |            |             | occupant)   |             |
   |            |            |             |             |             |
   | 24         | ZIP        | PC          | postal/zip  | 10027-1234  |
   |            |            |             | code        |             |
   |            |            |             |             |             |



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   | 25         |            |             | building    | LOW LIBRARY |
   |            |            |             | (structure) |             |
   |            |            |             |             |             |
   | 26         |            |             | unit        | APT 42      |
   |            |            |             | (apartment, |             |
   |            |            |             | suite)      |             |
   |            |            |             |             |             |
   | 27         |            | FLR         | floor       | 4           |
   |            |            |             |             |             |
   | 28         |            |             | room number | 450F        |
   |            |            |             |             |             |
   | 29         |            |             | placetype   | office      |
   |            |            |             |             |             |
   | 128        |            |             | script      | Latn        |
   |            |            |             |             |             |
   | 255        |            |             | reserved    |             |
   +------------+------------+-------------+-------------+-------------+

   The CA types labeled in the second column correspond to items from
   the NENA "Recommended Formats & Protocols For ALI Data Exchange, ALI
   Response & GIS Mapping" [16], but are applicable to most countries.
   The "NENA" column refers to the data dictionary name in Exhibit 18 of
   [16].

   The column labeled PIDF indicates the element name from [14].

   The "language" item (CAtype 0) optionally identifies the language
   used for presenting the address information, drawing from the tags
   for identifying languages in [7].  If omitted, the default value for
   this tag is "i-default" [3].

   The "script" item (CAtype 128) optionally identifies the script used
   for presenting the address information, drawing from the tags for
   identifying scripts in ISO 15924 [11].  If omitted, the default value
   for this tag is "Latn".

   The abbreviations N, E, S, W, and NE, NW, SE, SW should be used for
   POD and PRD in English-speaking countries.

   STS designates a street suffix.  In the United States (US), the
   abbreviations recommended by the United States Postal Service
   Publication 28 [15], Appendix C, SHOULD be used.

   HNS ("house number") is a modifier to a street address; it does not
   identify parts of a street address.

   LMK ("landmark") is a string name for a location.  It conveys the
   same information as the street address, but reflects common local



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   designation of a structure, a group of buildings or a place that
   helps recipients locate the place.  For example, an industrial park
   may have a widely-recognized name that is more readily found than a
   single street address.  Some places, such as parks, may not have
   street names or house numbers and SHOULD be identified by a LMK
   string.

   LOC ("location") is an unstructured string.

   The NAM object is used to aid user location ("Joe Miller" "Alice's
   Dry Cleaning").  It does not identify the person using a
   communications device, but rather the person or organization
   associated with the address.

   While a landmark (LMK) can indicate a complex of buildings,
   'building' (CAtype 25) conveys the name of a single building if the
   street address includes more than one building or the building name
   is helpful in identifying the location.  (For example, on university
   campuses, the house number is often not displayed on buildings, while
   the building name is prominently shown.)

   The 'unit' object (CAtype 26) contains the name or number of a part
   of a structure where there are separate administrative units, owners
   or tenants, such as separate companies or families who occupy that
   structure.  Common examples include suite or apartment designations.

   A 'room' is the smallest identifiable subdivision of a structure.

   The "type of place" item (CAtype 29) describes the type of place
   described by the civic coordinates.  For example, it describes
   whether it is a home, office, street or other public space.  The
   values are drawn from the items in the rich presence [17] document.
   This information makes it easy, for example, for the DHCP client to
   then populate the presence information.  Since this is an
   IANA-registered token, the language and script designations do not
   apply for this element.















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4.  Example

   Rather than showing the precise byte layout of a DHCP option, we show
   a symbolic example below, representing the civic address of the
   Munich city hall in Bavaria, Germany.  The city and state name are
   also conveyed in English and Italian in addition to German; the other
   items are assumed to be common across all languages.  All languages
   use the latin script.

                       +--------+---------------+
                       | CAtype | CAvalue       |
                       +--------+---------------+
                       | 0      | de            |
                       |        |               |
                       | 128    | Latn          |
                       |        |               |
                       | 1      | Bayern        |
                       |        |               |
                       | 2      | Oberbayern    |
                       |        |               |
                       | 3      | M=U+00FCnchen |
                       |        |               |
                       | 6      | Marienplatz   |
                       |        |               |
                       | 19     | 8             |
                       |        |               |
                       | 21     | Rathaus       |
                       |        |               |
                       | 24     | 80331         |
                       |        |               |
                       | 25     | public        |
                       |        |               |
                       | 0      | en            |
                       |        |               |
                       | 1      | Bavaria       |
                       |        |               |
                       | 3      | Munich        |
                       |        |               |
                       | 0      | it            |
                       |        |               |
                       | 1      | Baviera       |
                       |        |               |
                       | 3      | Monaco        |
                       +--------+---------------+







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5.  Security Considerations

   Where critical decisions might be based on the value of this
   GeoConf_Civic option, DHCP authentication in RFC3118 [4] SHOULD be
   used to protect the integrity of the DHCP options.

   Since there is no privacy protection for DHCP messages, an
   eavesdropper who can monitor the link between the DHCP server and
   requesting client can discover the information contained in this
   option.

   To minimize the unintended exposure of location information, the
   GeoConf_Civic option SHOULD be returned by DHCP servers only when the
   DHCP client has included this option in its 'parameter request list'
   (Section 3.5 [2]).

   When implementing a DHCP server that will serve clients across an
   uncontrolled network, one should consider the potential security
   risks.
































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6.  IANA Considerations

   This document requests that IANA register a new DHCPv4 and DHCPv6
   option code for the Civic Address (GEOCONF_CIVIC).

   This document establishes a new IANA registry for CAtypes designating
   civic address components.  According to RFC 2434 [12], this registry
   operates under the "Specification Required" rules.  The IANA
   registration needs to include the following information:

   CAType: 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 or
      other permanent and readily available reference, in sufficient
      detail so that interoperability between independent
      implementations is possible.
   Country-specific considerations: If applicable, notes whether the
      element is only applicable or defined for certain countries.
































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7.  References

7.1  Normative References

   [1]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
         Levels", BCP 14, RFC 2119, March 1997.

   [2]   Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
         March 1997.

   [3]   Alvestrand, H., "IETF Policy on Character Sets and Languages",
         BCP 18, RFC 2277, January 1998.

   [4]   Droms, R. and W. Arbaugh, "Authentication for DHCP Messages",
         RFC 3118, June 2001.

   [5]   Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M.
         Carney, "Dynamic Host Configuration Protocol for IPv6
         (DHCPv6)", RFC 3315, July 2003.

   [6]   Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD
         63, RFC 3629, November 2003.

   [7]   Alvestrand, H., "Tags for the Identification of Languages", BCP
         47, RFC 3066, January 2001.

   [8]   Lemon, T. and S. Cheshire, "Encoding Long Options in the
         Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396,
         November 2002.

   [9]   Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
         January 2004.

   [10]  Sugano, H. and S. Fujimoto, "Presence Information Data Format
         (PIDF)", draft-ietf-impp-cpim-pidf-08 (work in progress), May
         2003.

   [11]  International Organization for Standardization, ISO.,
         "Information and documentation - Codes for the representation
         of names of scripts", February 2004.

7.2  Informative References

   [12]  Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
         Considerations Section in RFCs", BCP 26, RFC 2434, October
         1998.

   [13]  Polk, J., Schnizlein, J. and M. Linsner, "Dynamic Host



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         Configuration Protocol Option for Coordinate-based Location
         Configuration Information", RFC 3825, July 2004.

   [14]  Peterson, J., "A Presence-based GEOPRIV Location Object
         Format", draft-ietf-geopriv-pidf-lo-03 (work in progress),
         September 2004.

   [15]  United States Postal Service, "Postal Addressing Standards",
         November 2000.

   [16]  National Emergency Number Assocation, "NENA Recommended Formats
         and Protocols For ALI Data Exchange, ALI Response and GIS
         Mapping", NENA NENA-02-010, January 2002.

   [17]  Schulzrinne, H., Gurbani, V., Kyzivat, P. and J. Rosenberg,
         "RPID: Rich Presence: Extensions to the Presence Information
         Data Format  (PIDF)", draft-ietf-simple-rpid-03 (work in
         progress), March 2004.


Author's Address

   Henning Schulzrinne
   Columbia University
   Department of Computer Science
   450 Computer Science Building
   New York, NY  10027
   US

   Phone: +1 212 939 7042
   EMail: hgs+simple@cs.columbia.edu
   URI:   http://www.cs.columbia.edu



















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Appendix A.  Acknowledgments

   Harald Alvestrand, Stefan Berger, Rohan Mahy and James Polk provided
   helpful comments.















































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