RFC 3017 Network Working Group M. Riegel Request for Comments: 3017 Siemens AG Category: Standards Track G. Zorn Cisco Systems December 2000 XML DTD for Roaming Access Phone Book 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) The Internet Society (2000). All Rights Reserved. Abstract This document defines the syntax as well as the semantics of the information to be included in the phone book for roaming applications. It comprises the information necessary to select the most appropriate ISP and to configure the host to get access to the network of the provider. The specification consists of a small set of required information elements and a variety of possible extensions. All data is specified in XML [5] (Extensible Markup Language) syntax leading to a concise XML DTD (Document Type Declaration) for the phone book. Table of Contents 1. Introduction ............................................. 3 2. Rationale for XML Usage .................................. 4 3. Specification of Requirements ............................ 5 4. Value type notations for 'stronger' typing ............... 5 5. Container Element Definitions ............................ 5 5.1. PhoneBook ............................................ 5 5.1.1. phoneBook Attribute "name" ........................ 6 5.1.2. phoneBook Attribute "version" ..................... 6 5.2. POP .................................................. 7 5.2.1. pop Attribute "entryVersion" ...................... 8 5.3. Setup ................................................ 8 5.4. Support .............................................. 9 5.5. Provider ............................................. 9 Riegel & Zorn Standards Track [Page 1] RFC 3017 Roaming Access Phone Book XML DTD December 2000 6. Information Element Definitions .......................... 10 6.1. Information elements defined for the POP element ..... 10 6.1.1. Address ........................................... 10 6.1.1.1. address Attribute "family" ..................... 10 6.1.1.2. address Attribute "countryCode" ................ 11 6.1.1.3. address Attribute "areaCode" ................... 11 6.1.2. Media ............................................. 11 6.1.2.1. Modem Protocols ................................ 12 6.1.2.2. ISDN Protocols ................................. 12 6.1.2.3. ATM Protocols .................................. 13 6.1.2.4. Frame Relay Protocols .......................... 13 6.1.2.5. X.25 Protocols ................................. 13 6.1.3. Minimum Data Rate ................................. 14 6.1.4. Maximum Data Rate ................................. 14 6.1.5. POP Properties .................................... 14 6.1.6. Tunneling Protocols ............................... 15 6.1.7. Dialing Script .................................... 15 6.1.8. Pricing Information ............................... 16 6.1.9. City .............................................. 16 6.1.10. Region ........................................... 16 6.1.11. Country .......................................... 16 6.1.12. POP Setup ........................................ 17 6.1.13. POP Support ...................................... 17 6.1.14. POP Provider ..................................... 17 6.2. Information elements defined for the Setup element ... 17 6.2.1. DNS Server Address ................................ 17 6.2.2. NNTP Server Name .................................. 18 6.2.3. SMTP Server Name .................................. 18 6.2.4. POP3 Server Name .................................. 18 6.2.5. IMAP Server Name .................................. 18 6.2.6. WWW Proxy ......................................... 19 6.2.7. FTP Proxy ......................................... 19 6.2.8. Winsock Proxy ..................................... 19 6.2.9. Default Gateway Address ........................... 19 6.2.10. User Name Suffix ................................. 20 6.2.11. User Name Prefix ................................. 20 6.3. Information elements defined for the support element.. 20 6.3.1. Support Telephone Number .......................... 20 6.3.2. Support Email Address ............................. 21 6.4. Information elements defined for the provider element. 21 6.4.1. Provider Name ..................................... 21 6.4.2. Provider Icon ..................................... 21 6.4.3. Provider's World Wide Web URL ..................... 21 6.4.4. Provider's Main Email Address ..................... 22 6.4.5. Billing Inquiry Email Address ..................... 22 6.4.6. Further elements .................................. 22 7. Complete XML DTD for the roaming phone book .............. 22 8. Security Considerations .................................. 28 Riegel & Zorn Standards Track [Page 2] RFC 3017 Roaming Access Phone Book XML DTD December 2000 9. IANA Considerations ...................................... 28 9.1. Registration of new attribute values ................. 29 9.2. Registration of new information elements ............. 29 10. References .............................................. 30 11. Appendix: Examples ...................................... 31 11.1. The most simple example ............................. 31 11.2. A more comprehensive example ........................ 31 12. Acknowledgments ......................................... 31 13. Authors' Addresses ...................................... 32 14. Full Copyright Statement ................................ 33 1. Introduction Roaming applications depend on the delivery of information about provided services and the procedures to get connected to the network from the roaming consortium to the individual users as well as from the operators of the network access servers, normally the members of the roaming consortium, and the roaming consortium. "phone book" +------+ +--+ | | | ++ | ISP1 | -- | | --+ | | +---+ \ "phone book" +------+ \ +------+ +------+ +--+ \_ | | +--+ +------+ | | | ++ | | | ++ | | | ISP2 | -- | | -->>--- | | --- | | ->> | USER | | | +---+ _ | | +---+ | | +------+ / | | +------+ +------+ +--+ / +------+ | | | ++ / Roaming | ISP# | -- | | --+ Consortium | | +---+ +------+ The roaming consortium assembles from the individual contributions of the providers belonging to the consortium a unified version of the phone book for usage by the customers. Probably different groups of users get different versions of a phone book adapted to their particular needs. Even users might generate different subsets especially suited to particular applications from the information received from the roaming consortium, e.g., retrieving only entries for a particular country or extracting all access points providing wireless connectivity. Riegel & Zorn Standards Track [Page 3] RFC 3017 Roaming Access Phone Book XML DTD December 2000 Therefore it is desirable to define a highly portable and well formed structure of the phone book to enable easy generation and postprocessing. Goals of this document include: - Creating a flexible, extensible and robust framework upon which to build a standard phone book; - Promoting a standard phone book format, to enhance interoperability between ISPs and roaming consortia as well as to enable automatic extraction of configuration data by a wide variety of devices; - Defining a compact structure containing the essential information for the roaming user, to allow for storage and easy update even on small devices. It is not intended by this document to create a plethoric solution, with phone book elements to fit every condition on earth, neither to define any kind of phone book update or transfer protocol. 2. Rationale for XML Usage XML is rapidly becoming a standard format for data exchange between different applications also taking into account the transfer and access of data over the web. XML is used as syntax for expressing the structure and content of a roaming phone book to enable widespread usage and access to many different kind of media (e.g., paper, CDROM, www) using a widespread selection of access devices. Furthermore XML enables: - Extensibility - Flexibility - Integration with directories Extensibility is important because phone books are living documents; as such, it is unlikely that all the semantic requirements of arbitrary Internet service providers (ISPs) would be met by a fixed scheme, no matter how well thought out. Phone book designers must be free to create new attributes in a well-understood fashion to meet changing business needs. Flexibility is required of the attribute definition syntax for many of the same reasons that semantic extensibility is necessary. If we assume that phone book designers may need to define elements of arbitrary type, the syntax chosen must be able to represent these data objects cleanly. Using XML for describing the data content of the phone book fits this bill nicely, since it can be used to unambiguously describe virtually any data type. Riegel & Zorn Standards Track [Page 4] RFC 3017 Roaming Access Phone Book XML DTD December 2000 Integration with directories: although it is unlikely that phone books will be stored in the directory due to performance considerations, the creation of a XML DTD describing phone book content leaves that option open, with relatively little incremental effort required to implement it. 3. Specification of Requirements In this document, the key words "MAY", "MUST, "MUST NOT", "optional", "recommended", "SHOULD", and "SHOULD NOT", are to be interpreted as described in [1]. 4. Value type notations for 'stronger' typing XML DTDs do not currently have capabilities for 'strong typing' of the content of elements. The only type definition foreseen in the base specification is "#PCDATA", 'parsable character data'. This might be sufficient and is used throughout this document to define elements containing information mainly aimed for interpretation by human beings. To enable a more concise description of the content of particular elements several value type notations are introduced. This allows for a more detailed type description of the content of elements in cases where it seems to be desirable. 5. Container Element Definitions 5.1. PhoneBook The phoneBook element is the basic container for phone book entries. It has two attributes, a phone book name and a phone book version number (applying to the phone book as a whole), and always contains one or more pop elements. A phoneBook element may also contain multiple Setup, Support and Provider elements, if they are referenced to by more than one pop element. Riegel & Zorn Standards Track [Page 5] RFC 3017 Roaming Access Phone Book XML DTD December 2000 Syntax: phoneBook +-----------------------------------+ | phoneBookName (req)| | phoneBookVersion (req)| | +-----------------------+ | | | pop |+ (req)| | +-----------------------+| | | + - - - - - - - - - - - + | | | | + - - - - - - - - - - - + | | | setup |+ (opt)| | + - - - - - - - - - - - +| | | + - - - - - - - - - - - + | | | | + - - - - - - - - - - - + | | | support |+ (opt)| | + - - - - - - - - - - - +| | | + - - - - - - - - - - - + | | | | + - - - - - - - - - - - + | | | provider |+ (opt)| | + - - - - - - - - - - - +| | | + - - - - - - - - - - - + | +-----------------------------------+ 5.1.1. phoneBook Attribute "name" The phoneBook attribute "name" is an arbitrary string assigned as an identifier for a phone book. 5.1.2. phoneBook Attribute "version" The phoneBookVersion attribute is an integer representing the version of the phone book; it is a monotonically increasing counter which should be incremented each time the phone book is modified. This element can be used by a server to help decide what (if any) actions are required to bring a client's phone book up to date. For example, the client can, at connect time, send an update request to the server Riegel & Zorn Standards Track [Page 6] RFC 3017 Roaming Access Phone Book XML DTD December 2000 including in the request the version number of its current phone book. If the client's phone book version is not the same as the server's current phone book version, the server can easily take appropriate action, e.g., reply with a URL pointing to a file containing the differences between the client and server phone books. 5.2. POP The pop element contains information elements relevant to individual network points of presence (POPs). The required information elements are addrFamily, address, media and entryVersion. The media element represents the media types supported by the POP, while the entryVersion element is a monotonically-increasing integer which should be incremented whenever the object is modified. The following information elements are currently defined for the pop element. Additional information elements may be defined by IANA in future. POP +-----------------------------------+ | entryVersion (req)| | +-------------------------+ | | | address | (req)| | +-------------------------+ | | media (req)| | minBitsPerSecond (opt)| | maxBitsPerSecond (opt)| | "popProperties" (opt)| | "tunnelingProtocols" (opt)| | dialScript (opt)| | pricingInformation (opt)| | + - - - - - - - - - - - - + | | | "location" | (opt)| | + - - - - - - - - - - - - + | | + - - - - - - - - - - - - + | | | "popSetup" | (opt)| | + - - - - - - - - - - - - + | | + - - - - - - - - - - - - + | | | "popSupport" | (opt)| | + - - - - - - - - - - - - + | | + - - - - - - - - - - - - + | | | "popProvider" | (opt)| | + - - - - - - - - - - - - + | +-----------------------------------+ Riegel & Zorn Standards Track [Page 7] RFC 3017 Roaming Access Phone Book XML DTD December 2000 Syntax: 5.2.1. pop Attribute "entryVersion" The entryVersion attribute is an integer representing the version of the POP object; it is a monotonically increasing counter which should be incremented each time the object is modified. This attribute may be useful in merging and updating phone books. 5.3. Setup The Setup element includes information elements which describe services which may change from provider to provider or even from POP to POP. Some of the values contained in these information elements may be available by other means (e.g., DHCP), but others may not. The following information elements are currently defined for the Setup element. Additional information elements may be defined by IANA in future. Syntax: 5.4. Support The Support element includes those information elements that are pertinent to the provision of customer support for a POP or provider. Languages spoken by the staff at the support center might be specified by multiple entries for the attribute value language. Additional information elements for the Support element may be defined by IANA in future. Syntax: 5.5. Provider The Provider element contains information elements pertaining to the general business operations of a given network service provider. The information elements include such things as telephone number, mailing address, etc., as well as URLs for e-mail and a World Wide Web site. A Provider element may also contain a reference to support information. Currently the following information elements are defined for the Provider element. Additional information elements may be defined by IANA in future. Syntax: 6. Information Element Definitions 6.1. Information elements defined for the POP element 6.1.1. Address The address element provides the information representing the address of the POP. For POPs offering dial-up network access, the address element will at least contain an IA5 string representing a telephone number, formatted in standard fashion [4] (e.g., "+ 1 234 5678"). More detailed information may be available by optional attribute values. Syntax: 6.1.1.1. address Attribute "family" The attribute family of the element address defines the address family to which the element value belongs. For POPs offering dial-up network access, the addrFamily attribute will generally contain a value for a telephone network based address family. Currently the following attribute values are defined. Additional values may be Riegel & Zorn Standards Track [Page 10] RFC 3017 Roaming Access Phone Book XML DTD December 2000 registered by IANA in future. Value Description ------ ------------------------------------------ E164 ITU-T E.164 (PSTN, SMDS, Frame Relay, ATM) X121 ITU-T X.121 (X.25, Frame Relay) Syntax: 6.1.1.2. address Attribute "countryCode" The countryCode attribute indicates the international dialing prefix for the country in which the POP is located. Syntax: 6.1.1.3. address Attribute "areaCode" The areaCode attribute contains the area or city code component of the telephone number in the 'address' element (if any) associated with this POP. 6.1.2. Media The media element is a container describing the types of media and related protocols supported by this POP. The following media types are currently defined. Additional types may be registered by IANA in future. Value Media Type -------- ----------- viaMODEM Modem viaISDN ISDN viaATM ATM viaFR Frame Relay viaX25 X.25 Riegel & Zorn Standards Track [Page 11] RFC 3017 Roaming Access Phone Book XML DTD December 2000 Syntax: 6.1.2.1. Modem Protocols The viaMODEM element is an empty element representing by its optional type attribute the modem protocol supported by the access devices that can be reached at address. To define multiple available protocols this element may be included repeatedly. The initially defined modem protocol types are listed in the table below. Additional values may be registered by IANA in future. Value Duplex Speed Protocol ----- ------ ----- ------------- V21 Full 300 ITU-T V.21 V22 Full 1200 ITU-T V.22 V29 Half 9600 ITU-T V.29 V32 Full 9600 ITU-T V.32 V32B Full 14.4k ITU-T V.32bis V34 Full 28.8k ITU-T V.34 V34B Full 33.6k ITU-T V.34bis V90 Full 56k ITU-T V.90 Syntax 6.1.2.2. ISDN Protocols The viaISDN element is an empty element representing by its optional type attribute the ISDN protocol supported by the access devices that can be reached at address. To define multiple available protocols this element may be included repeatedly. The initially defined ISDN protocol types are listed in the table below. Additional values may be registered by IANA in future. Value Speed Meaning ----- ----- ----------- V110L 19.2k ITU-T V.110 V110H 38.4k ITU-T V.110 V120L 56k ITU-T V.120 Riegel & Zorn Standards Track [Page 12] RFC 3017 Roaming Access Phone Book XML DTD December 2000 V120H 64k ITU-T V.120 X75 64k ITU-T X.75 HDLC 64k RFC 1618 Syntax: 6.1.2.3. ATM Protocols The viaATM element is an empty element representing by its optional type attribute a particular protocol supported by the access devices that can be reached at address. To define multiple available protocols this element may be included repeatedly. Currently only one protocol is defined. Additional values may be registered by IANA in future. Syntax: 2364)"> 6.1.2.4. Frame Relay Protocols The viaFR element is an empty element representing by its optional type attribute the particular protocol supported by the access devices that can be reached at address. To define multiple available protocols this element may be included repeatedly. Currently only one protocol is defined. Additional values may be registered by IANA in future. Syntax: 1973)"> 6.1.2.5. X.25 Protocols The viaX25 element is an empty element representing by its optional type attribute the particular protocol supported by the access devices that can be reached at address. To define multiple available Riegel & Zorn Standards Track [Page 13] RFC 3017 Roaming Access Phone Book XML DTD December 2000 protocols this element may be included repeatedly. Currently only one protocol is defined. Additional values may be registered by IANA in future. Syntax: 1598)"> 6.1.3. Minimum Data Rate The minBitsPerSecond element indicates the minimum data rate (in bits/second) supported by the access devices at the POP. Syntax: 6.1.4. Maximum Data Rate The maxBitsPerSecond element indicates the maximum data rate (in bits/second) supported by the access devices at the POP. Syntax: 6.1.5. POP Properties The popProperty element is an empty element representing by its attribute value a particular property of this POP. To define multiple available protocols this element might be included several times. The initially defined properties are listed in the table below. Additional values may be registered by IANA in future. Value Property ------ ---------------------- MPPP Multilink PPP (RFC 1990) MOBIP Mobile IP (RFC 2002) MCRX Multicast Reception MCTX Multicast Transmission Syntax: Riegel & Zorn Standards Track [Page 14] RFC 3017 Roaming Access Phone Book XML DTD December 2000 6.1.6. Tunneling Protocols The tunnelProto element is an empty element representing by its attribute a tunneling protocol supported by this POP. To define multiple available protocols this element might be included several times. The initially defined values are listed in the table below. Additional values may be registered by IANA in future. Value Protocol ------ ------------------ L2TP RFC 2661 L2TP PPTP RFC 2637 PPTP L2F RFC 2341 L2F ATMP RFC 2107 ATMP AHT RFC 2402 IP AH Tunnel Mode ESPT RFC 2406 IP ESP Tunnel Mode IPIP RFC 1853 IP-IP MIP RFC 2004 Minimal IP-IP GRE RFC 1701 GRE Syntax: 6.1.7. Dialing Script The dialScript element contains the dialing script to be used when connecting to this POP. The attribute value type of dialScript defines the type of the script that should be used when connecting to this POP. Syntax: Riegel & Zorn Standards Track [Page 15] RFC 3017 Roaming Access Phone Book XML DTD December 2000 6.1.8. Pricing Information The pricingInformation element is a free-form string representing pricing information for this POP. It may be anything from a simple string indicating relative expense (e.g., "$$$$" for a very expensive POP) to a paragraph describing time-of-day and other differential pricing variables. Syntax: 6.1.9. City The city element contains the name of the city in which the POP is located (not the city(s) from which it is accessible by a local call). Syntax: 6.1.10. Region The region element contains the name of the region in which the POP is located. In the United States, this would be the name of a state or (for Washington, D.C.) administrative district. In other countries, it might be the name of a province, parish or county. Syntax: 6.1.11. Country The country element contains the name of the country in which the POP is located. The country name may be abbreviated (e.g., "USA" for the United States of America or "UK" for the United Kingdom) but if abbreviations are used the usage must be consistent within a given phone book. Syntax: Riegel & Zorn Standards Track [Page 16] RFC 3017 Roaming Access Phone Book XML DTD December 2000 6.1.12. POP Setup The popSetup element is either a setup element, if setup is specific to this particular POP, or a reference to any of the setup elements given in the outer scope of the phonebook element. Syntax: 6.1.13. POP Support The popSupport element is either a support element, if support is specific to this particular POP, or a reference to any of the support elements given in the outer scope of the phonebook element. Syntax: 6.1.14. POP Provider The popProvider element is either a provider element, if provider information is specific to this particular POP, or a reference to any of the provider elements given in the outer scope of the phonebook element. Syntax: 6.2. Information elements defined for the Setup element 6.2.1. DNS Server Address The dnsServerAddress element represents the IP address of the Domain Name Service (DNS) server which should be used when connected to this POP. The address is represented in the form of a string in dotted- decimal notation (e.g., 192.168.101.1). Riegel & Zorn Standards Track [Page 17] RFC 3017 Roaming Access Phone Book XML DTD December 2000 Syntax: 6.2.2. NNTP Server Name The nntpServerName element contains the fully qualified domain name (FQDN) of the Network News Transfer Protocol (NNTP) server which should be used when connected to this POP. Syntax: 6.2.3. SMTP Server Name The smtpServerName element contains the FQDN of the Simple Mail Transfer Protocol (SMTP) server which should be used when connected to this POP. Syntax: 6.2.4. POP3 Server Name The popServerName element contains the FQDN of the Post Office Protocol (POP) server which should be used when connected to this POP. Syntax: 6.2.5. IMAP Server Name The imapServerName element contains the FQDN of the Internet Mail Access Protocol (IMAP) server which should be used when connected to this POP. Riegel & Zorn Standards Track [Page 18] RFC 3017 Roaming Access Phone Book XML DTD December 2000 Syntax: 6.2.6. WWW Proxy The wwwProxyServerName element contains the FQDN of the World Wide Web (WWW) proxy server which should be used when connected to this POP. Syntax: 6.2.7. FTP Proxy The ftpProxyServerName element contains the FQDN of the File Transfer Protocol (FTP) proxy server which should be used when connected to this POP. Syntax: 6.2.8. Winsock Proxy The winsockProxyServerName element contains the FQDN of the Windows Socket (Winsock) proxy server which should be used when connected to this POP. Syntax: 6.2.9. Default Gateway Address The defaulttGatewayAddress element represents the address of the default gateway which should be used when connected to this POP. The address is represented in the form of a string in dotted-decimal notation (e.g., 192.168.101.1). Riegel & Zorn Standards Track [Page 19] RFC 3017 Roaming Access Phone Book XML DTD December 2000 Syntax: 6.2.10. User Name Suffix The userNameSuffix element represents a string which should be concatenated to the base username. For example, if the base username is "userA" and the value of this element is "@bigco.com", the resulting augmented username would be "userA@bigco.com". An intelligent dialer may concatenate the string automatically. Note that both the userNameSuffix and the userNamePrefix (below) may be applied to the same base username. Syntax: 6.2.11. User Name Prefix The userNamePrefix element represents a string to which the base username should be concatenated. For example, if the base username is "userB" and the value of this element is "BIGCO/" the resulting augmented username would be "BIGCO/userB". An intelligent dialer may perform the concatenation automatically. Note that both the userNameSuffix (above) and the userNamePrefix may be applied to the same base username. Syntax: 6.3. Information elements defined for the support element 6.3.1. Support Telephone Number The supportTelephoneNumber element contains a number that may be called to reach the support center for a particular provider or POP. This element is basically a string and should contain the entire telephone number in international form, e.g., "+1 425 838 8080". Syntax: Riegel & Zorn Standards Track [Page 20] RFC 3017 Roaming Access Phone Book XML DTD December 2000 6.3.2. Support Email Address The supportMailtoURL element contains a URL for the provider's customer support email address, e.g., mailto:support@uu.net. This URL could be used to contact customer support personnel regarding non-urgent issues. Syntax: 6.4. Information elements defined for the provider element 6.4.1. Provider Name The providerName element is a string containing the name of the provider (e.g., "BIGNET Corporation"). Syntax: 6.4.2. Provider Icon The providerIcon attribute contains a BASE64 encoded JPEG or GIF image which may be used for 'branding' phone book entries or displayed when dialing. Syntax: 6.4.3. Provider's World Wide Web URL The wwwURL element contains a Uniform Resource Locator (URL) for the provider's Web site, for example, http://www.uu.net. Syntax: Riegel & Zorn Standards Track [Page 21] RFC 3017 Roaming Access Phone Book XML DTD December 2000 6.4.4. Provider's Main Email Address The generalMailtoURL element contains a URL for the provider's main email address, for example, mailto:contact@uu.net. This URL could be used for general correspondence, complaints, etc. Syntax: 6.4.5. Billing Inquiry Email Address The billingMailtoURL element contains a URL for the provider's billing support email address, for example, mailto:billing@uu.net. This URL could be used to for correspondence regarding billing and payment issues. Syntax: 6.4.6. Further elements The remainder of the information elements of the provider element are described in principle in [3]. 7. Complete XML DTD for the roaming phone book 2364)"> Riegel & Zorn Standards Track [Page 22] RFC 3017 Roaming Access Phone Book XML DTD December 2000 1973)"> 1598)"> Riegel & Zorn Standards Track [Page 24] RFC 3017 Roaming Access Phone Book XML DTD December 2000 Riegel & Zorn Standards Track [Page 25] RFC 3017 Roaming Access Phone Book XML DTD December 2000 Riegel & Zorn Standards Track [Page 26] RFC 3017 Roaming Access Phone Book XML DTD December 2000 Riegel & Zorn Standards Track [Page 27] RFC 3017 Roaming Access Phone Book XML DTD December 2000 8. Security Considerations The secure distribution and transport of information of a phone book for roaming applications require a reliable authentication of the issuer of the information as well as means to preserve the integrity of the provided information. No specific elements for security requirements are provided by the phone book XML DTD itself. It is assumed that security of the roaming phone book is provided by means outside of the scope of this specification, such as signing the phone book using pgp. 9. IANA Considerations This specification provides the possibility to define further attribute values for all information elements owning enumerated attribute lists as well as to extend the main structures 'pop', 'setup', 'support' and 'provider' by additional information elements. Therefore the specification of the roaming phone book can be adopted to future requirements without changing this document. Extensions and refinements to this specification can be achieved by registration of new elements and attributes by IANA. Extending this specification with additional attributes or elements must not change the validity of documents based on an older version of the XML DTD. Therefore all added information elements must be Riegel & Zorn Standards Track [Page 28] RFC 3017 Roaming Access Phone Book XML DTD December 2000 optional, prohibiting the mandatory inclusion of newly defined information elements. Adding new values to enumerated attribute lists has no backward compatibility constraints because it does not harm the validity of attributes already defined. To facilitate the registration of new information elements and attribute values the DTD of the phone book has been separated in two parts, the extensible part containing only parameter entity declarations for ease inclusion of new values, and the fixed part containing the detailed specification of the content and structure of the phone book. By referencing the parameter entity declarations in the fixed part of the specification the whole phone book becomes extensible. The part containing the parameter entity declarations has to be maintained by the IANA. There are two different classes of declarations in this part requiring different policies for registering new values. 9.1. Registration of new attribute values The entities 'addressFamily', 'modemProtocols', 'isdnProtocols', 'atmProtocols', 'frProtocols', 'x25Protocols', 'popProperties' and 'tunnelingProtocols' are describing enumerated attribute value lists. Because there is no limitation in the name space of these attribute values and newly defined attribute values can not harm the validity of existing values, new attribute values can be assigned by Specification Required [6]. 9.2. Registration of new information elements The entities 'mediaTypes', 'popInformation', 'setupInformation', ' supportInformation' and 'providerInformation' define the information elements probably included in the media, pop, setup, support and provider elements. Inserting new values into these lists extends the phone book by arbitrarily new information elements. Inappropriate use of the XML content model can destroy the backward compatibility of the DTD. Therefore the assignment of new information elements requires the approval of a Designated Expert [6]. In addition to the insertion of a new value into the list, the detailed definition of the information element has to be appended to the specification part maintained by the IANA. Riegel & Zorn Standards Track [Page 29] RFC 3017 Roaming Access Phone Book XML DTD December 2000 10. References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Reynolds, J. and J. Postel, "ASSIGNED NUMBERS", STD 2, RFC 1700, October 1994. [3] Barker, P. and S. Kille, "The COSINE and Internet X.500 Schema", RFC 1274, November 1991. [4] ITU Rec. E.123, "Notation for national and international telephone numbers", 1988. [5] "Extensible Markup Language (XML) 1.0" W3C Recommendation 10- February-1998 http://www.w3.org/TR/1998/REC-xml-19980210 [6] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October 1998. Riegel & Zorn Standards Track [Page 30] RFC 3017 Roaming Access Phone Book XML DTD December 2000 11. Appendix: Examples 11.1. The most simple example11.2. A more comprehensive example +1 234 5678901 12. Acknowledgments Thanks to Pat Calhoun, Bernard Aboba, Jay Farhat, Butch Anton, Quentin Miller, and Ken Crocker for salient input and review. Riegel & Zorn Standards Track [Page 31] RFC 3017 Roaming Access Phone Book XML DTD December 2000 13. Authors' Addresses Questions about this memo can be directed to: Max Riegel Siemens AG Hofmannstr. 51 Munich, 81359 Germany Phone: +49 89 722 49557 EMail: maximilian.riegel@icn.siemens.de Glen Zorn Cisco Systems, Inc. 500 108th Avenue N.E., Suite 500 Bellevue, WA 98004 USA Phone: +1 425 438 8218 EMail: gwz@cisco.com Riegel & Zorn Standards Track [Page 32] RFC 3017 Roaming Access Phone Book XML DTD December 2000 14. Full Copyright Statement Copyright (C) The Internet Society (2000). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Riegel & Zorn Standards Track [Page 33] +49913130540 192.168.147.5 193.175.24.33 mailto:support@franken.de +499123968066