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Network Working Group                                        S. PfeifferRequest for Comments: 3533                                         CSIROCategory: Informational                                         May 2003The Ogg Encapsulation Format Version 0Status of this Memo   This memo provides information for the Internet community.  It does   not specify an Internet standard of any kind.  Distribution of this   memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2003).  All Rights Reserved.Abstract   This document describes the Ogg bitstream format version 0, which is   a general, freely-available encapsulation format for media streams.   It is able to encapsulate any kind and number of video and audio   encoding formats as well as other data streams in a single bitstream.Terminology   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 inBCP 14,RFC 2119 [2].Table of Contents1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .22. Definitions  . . . . . . . . . . . . . . . . . . . . . . . . .23. Requirements for a generic encapsulation format  . . . . . . .34. The Ogg bitstream format . . . . . . . . . . . . . . . . . . .35. The encapsulation process  . . . . . . . . . . . . . . . . . .66. The Ogg page format  . . . . . . . . . . . . . . . . . . . . .97. Security Considerations  . . . . . . . . . . . . . . . . . . .118. References . . . . . . . . . . . . . . . . . . . . . . . . . .12A. Glossary of terms and abbreviations  . . . . . . . . . . . . .13B. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .14      Author's Address . . . . . . . . . . . . . . . . . . . . . . .14      Full Copyright Statement . . . . . . . . . . . . . . . . . . .15Pfeiffer                     Informational                      [Page 1]

RFC 3533                          OGG                           May 20031. Introduction   The Ogg bitstream format has been developed as a part of a larger   project aimed at creating a set of components for the coding and   decoding of multimedia content (codecs) which are to be freely   available and freely re-implementable, both in software and in   hardware for the computing community at large, including the Internet   community.  It is the intention of the Ogg developers represented by   Xiph.Org that it be usable without intellectual property concerns.   This document describes the Ogg bitstream format and how to use it to   encapsulate one or several media bitstreams created by one or several   encoders.  The Ogg transport bitstream is designed to provide   framing, error protection and seeking structure for higher-level   codec streams that consist of raw, unencapsulated data packets, such   as the Vorbis audio codec or the upcoming Tarkin and Theora video   codecs.  It is capable of interleaving different binary media and   other time-continuous data streams that are prepared by an encoder as   a sequence of data packets.  Ogg provides enough information to   properly separate data back into such encoder created data packets at   the original packet boundaries without relying on decoding to find   packet boundaries.   Please note that the MIME type application/ogg has been registered   with the IANA [1].2. Definitions   For describing the Ogg encapsulation process, a set of terms will be   used whose meaning needs to be well understood.  Therefore, some of   the most fundamental terms are defined now before we start with the   description of the requirements for a generic media stream   encapsulation format, the process of encapsulation, and the concrete   format of the Ogg bitstream.  See the Appendix for a more complete   glossary.   The result of an Ogg encapsulation is called the "Physical (Ogg)   Bitstream".  It encapsulates one or several encoder-created   bitstreams, which are called "Logical Bitstreams".  A logical   bitstream, provided to the Ogg encapsulation process, has a   structure, i.e., it is split up into a sequence of so-called   "Packets".  The packets are created by the encoder of that logical   bitstream and represent meaningful entities for that encoder only   (e.g., an uncompressed stream may use video frames as packets).  They   do not contain boundary information - strung together they appear to   be streams of random bytes with no landmarks.Pfeiffer                     Informational                      [Page 2]

RFC 3533                          OGG                           May 2003   Please note that the term "packet" is not used in this document to   signify entities for transport over a network.3. Requirements for a generic encapsulation format   The design idea behind Ogg was to provide a generic, linear media   transport format to enable both file-based storage and stream-based   transmission of one or several interleaved media streams independent   of the encoding format of the media data.  Such an encapsulation   format needs to provide:   o  framing for logical bitstreams.   o  interleaving of different logical bitstreams.   o  detection of corruption.   o  recapture after a parsing error.   o  position landmarks for direct random access of arbitrary positions      in the bitstream.   o  streaming capability (i.e., no seeking is needed to build a 100%      complete bitstream).   o  small overhead (i.e., use no more than approximately 1-2% of      bitstream bandwidth for packet boundary marking, high-level      framing, sync and seeking).   o  simplicity to enable fast parsing.   o  simple concatenation mechanism of several physical bitstreams.   All of these design considerations have been taken into consideration   for Ogg.  Ogg supports framing and interleaving of logical   bitstreams, seeking landmarks, detection of corruption, and stream   resynchronisation after a parsing error with no more than   approximately 1-2% overhead.  It is a generic framework to perform   encapsulation of time-continuous bitstreams.  It does not know any   specifics about the codec data that it encapsulates and is thus   independent of any media codec.4. The Ogg bitstream format   A physical Ogg bitstream consists of multiple logical bitstreams   interleaved in so-called "Pages".  Whole pages are taken in order   from multiple logical bitstreams multiplexed at the page level.  The   logical bitstreams are identified by a unique serial number in thePfeiffer                     Informational                      [Page 3]

RFC 3533                          OGG                           May 2003   header of each page of the physical bitstream.  This unique serial   number is created randomly and does not have any connection to the   content or encoder of the logical bitstream it represents.  Pages of   all logical bitstreams are concurrently interleaved, but they need   not be in a regular order - they are only required to be consecutive   within the logical bitstream.  Ogg demultiplexing reconstructs the   original logical bitstreams from the physical bitstream by taking the   pages in order from the physical bitstream and redirecting them into   the appropriate logical decoding entity.   Each Ogg page contains only one type of data as it belongs to one   logical bitstream only.  Pages are of variable size and have a page   header containing encapsulation and error recovery information.  Each   logical bitstream in a physical Ogg bitstream starts with a special   start page (bos=beginning of stream) and ends with a special page   (eos=end of stream).   The bos page contains information to uniquely identify the codec type   and MAY contain information to set up the decoding process.  The bos   page SHOULD also contain information about the encoded media - for   example, for audio, it should contain the sample rate and number of   channels.  By convention, the first bytes of the bos page contain   magic data that uniquely identifies the required codec.  It is the   responsibility of anyone fielding a new codec to make sure it is   possible to reliably distinguish his/her codec from all other codecs   in use.  There is no fixed way to detect the end of the codec-   identifying marker.  The format of the bos page is dependent on the   codec and therefore MUST be given in the encapsulation specification   of that logical bitstream type.  Ogg also allows but does not require   secondary header packets after the bos page for logical bitstreams   and these must also precede any data packets in any logical   bitstream.  These subsequent header packets are framed into an   integral number of pages, which will not contain any data packets.   So, a physical bitstream begins with the bos pages of all logical   bitstreams containing one initial header packet per page, followed by   the subsidiary header packets of all streams, followed by pages   containing data packets.   The encapsulation specification for one or more logical bitstreams is   called a "media mapping".  An example for a media mapping is "Ogg   Vorbis", which uses the Ogg framework to encapsulate Vorbis-encoded   audio data for stream-based storage (such as files) and transport   (such as TCP streams or pipes).  Ogg Vorbis provides the name and   revision of the Vorbis codec, the audio rate and the audio quality on   the Ogg Vorbis bos page.  It also uses two additional header pages   per logical bitstream.  The Ogg Vorbis bos page starts with the byte   0x01, followed by "vorbis" (a total of 7 bytes of identifier).Pfeiffer                     Informational                      [Page 4]

RFC 3533                          OGG                           May 2003   Ogg knows two types of multiplexing: concurrent multiplexing (so-   called "Grouping") and sequential multiplexing (so-called   "Chaining").  Grouping defines how to interleave several logical   bitstreams page-wise in the same physical bitstream.  Grouping is for   example needed for interleaving a video stream with several   synchronised audio tracks using different codecs in different logical   bitstreams.  Chaining on the other hand, is defined to provide a   simple mechanism to concatenate physical Ogg bitstreams, as is often   needed for streaming applications.   In grouping, all bos pages of all logical bitstreams MUST appear   together at the beginning of the Ogg bitstream.  The media mapping   specifies the order of the initial pages.  For example, the grouping   of a specific Ogg video and Ogg audio bitstream may specify that the   physical bitstream MUST begin with the bos page of the logical video   bitstream, followed by the bos page of the audio bitstream.  Unlike   bos pages, eos pages for the logical bitstreams need not all occur   contiguously.  Eos pages may be 'nil' pages, that is, pages   containing no content but simply a page header with position   information and the eos flag set in the page header.  Each grouped   logical bitstream MUST have a unique serial number within the scope   of the physical bitstream.   In chaining, complete logical bitstreams are concatenated.  The   bitstreams do not overlap, i.e., the eos page of a given logical   bitstream is immediately followed by the bos page of the next.  Each   chained logical bitstream MUST have a unique serial number within the   scope of the physical bitstream.   It is possible to consecutively chain groups of concurrently   multiplexed bitstreams.  The groups, when unchained, MUST stand on   their own as a valid concurrently multiplexed bitstream.  The   following diagram shows a schematic example of such a physical   bitstream that obeys all the rules of both grouped and chained   multiplexed bitstreams.               physical bitstream with pages of          different logical bitstreams grouped and chained      -------------------------------------------------------------      |*A*|*B*|*C*|A|A|C|B|A|B|#A#|C|...|B|C|#B#|#C#|*D*|D|...|#D#|      -------------------------------------------------------------       bos bos bos             eos           eos eos bos       eos   In this example, there are two chained physical bitstreams, the first   of which is a grouped stream of three logical bitstreams A, B, and C.   The second physical bitstream is chained after the end of the grouped   bitstream, which ends after the last eos page of all its grouped   logical bitstreams.  As can be seen, grouped bitstreams beginPfeiffer                     Informational                      [Page 5]

RFC 3533                          OGG                           May 2003   together - all of the bos pages MUST appear before any data pages.   It can also be seen that pages of concurrently multiplexed bitstreams   need not conform to a regular order.  And it can be seen that a   grouped bitstream can end long before the other bitstreams in the   group end.   Ogg does not know any specifics about the codec data except that each   logical bitstream belongs to a different codec, the data from the   codec comes in order and has position markers (so-called "Granule   positions").  Ogg does not have a concept of 'time': it only knows   about sequentially increasing, unitless position markers.  An   application can only get temporal information through higher layers   which have access to the codec APIs to assign and convert granule   positions or time.   A specific definition of a media mapping using Ogg may put further   constraints on its specific use of the Ogg bitstream format.  For   example, a specific media mapping may require that all the eos pages   for all grouped bitstreams need to appear in direct sequence.  An   example for a media mapping is the specification of "Ogg Vorbis".   Another example is the upcoming "Ogg Theora" specification which   encapsulates Theora-encoded video data and usually comes multiplexed   with a Vorbis stream for an Ogg containing synchronised audio and   video.  As Ogg does not specify temporal relationships between the   encapsulated concurrently multiplexed bitstreams, the temporal   synchronisation between the audio and video stream will be specified   in this media mapping.  To enable streaming, pages from various   logical bitstreams will typically be interleaved in chronological   order.5. The encapsulation process   The process of multiplexing different logical bitstreams happens at   the level of pages as described above.  The bitstreams provided by   encoders are however handed over to Ogg as so-called "Packets" with   packet boundaries dependent on the encoding format.  The process of   encapsulating packets into pages will be described now.   From Ogg's perspective, packets can be of any arbitrary size.  A   specific media mapping will define how to group or break up packets   from a specific media encoder.  As Ogg pages have a maximum size of   about 64 kBytes, sometimes a packet has to be distributed over   several pages.  To simplify that process, Ogg divides each packet   into 255 byte long chunks plus a final shorter chunk.  These chunks   are called "Ogg Segments".  They are only a logical construct and do   not have a header for themselves.Pfeiffer                     Informational                      [Page 6]

RFC 3533                          OGG                           May 2003   A group of contiguous segments is wrapped into a variable length page   preceded by a header.  A segment table in the page header tells about   the "Lacing values" (sizes) of the segments included in the page.  A   flag in the page header tells whether a page contains a packet   continued from a previous page.  Note that a lacing value of 255   implies that a second lacing value follows in the packet, and a value   of less than 255 marks the end of the packet after that many   additional bytes.  A packet of 255 bytes (or a multiple of 255 bytes)   is terminated by a lacing value of 0.  Note also that a 'nil' (zero   length) packet is not an error; it consists of nothing more than a   lacing value of zero in the header.   The encoding is optimized for speed and the expected case of the   majority of packets being between 50 and 200 bytes large.  This is a   design justification rather than a recommendation.  This encoding   both avoids imposing a maximum packet size as well as imposing   minimum overhead on small packets.  In contrast, e.g., simply using   two bytes at the head of every packet and having a max packet size of   32 kBytes would always penalize small packets (< 255 bytes, the   typical case) with twice the segmentation overhead.  Using the lacing   values as suggested, small packets see the minimum possible byte-   aligned overhead (1 byte) and large packets (>512 bytes) see a fairly   constant ~0.5% overhead on encoding space.Pfeiffer                     Informational                      [Page 7]

RFC 3533                          OGG                           May 2003   The following diagram shows a schematic example of a media mapping   using Ogg and grouped logical bitstreams:          logical bitstream with packet boundaries ----------------------------------------------------------------- > |       packet_1             | packet_2         | packet_3 |  < -----------------------------------------------------------------                     |segmentation (logically only)                     v      packet_1 (5 segments)          packet_2 (4 segs)    p_3 (2 segs)     ------------------------------ -------------------- ------------ ..  |seg_1|seg_2|seg_3|seg_4|s_5 | |seg_1|seg_2|seg_3|| |seg_1|s_2 | ..     ------------------------------ -------------------- ------------                     | page encapsulation                     v page_1 (packet_1 data)   page_2 (pket_1 data)   page_3 (packet_2 data)------------------------  ----------------  ------------------------|H|------------------- |  |H|----------- |  |H|------------------- ||D||seg_1|seg_2|seg_3| |  |D|seg_4|s_5 | |  |D||seg_1|seg_2|seg_3| | ...|R|------------------- |  |R|----------- |  |R|------------------- |------------------------  ----------------  ------------------------                    |pages of            |other    --------|  |logical         -------bitstreams      | MUX |                -------                   |                   v              page_1  page_2          page_3      ------  ------  -------  -----  ------- ...  ||   |  ||   |  ||    |  ||  |  ||    |  ...      ------  ------  -------  -----  -------              physical Ogg bitstream   In this example we take a snapshot of the encapsulation process of   one logical bitstream.  We can see part of that bitstream's   subdivision into packets as provided by the codec.  The Ogg   encapsulation process chops up the packets into segments.  The   packets in this example are rather large such that packet_1 is split   into 5 segments - 4 segments with 255 bytes and a final smaller one.   Packet_2 is split into 4 segments - 3 segments with 255 bytes and aPfeiffer                     Informational                      [Page 8]

RFC 3533                          OGG                           May 2003   final very small one - and packet_3 is split into two segments.  The   encapsulation process then creates pages, which are quite small in   this example.  Page_1 consists of the first three segments of   packet_1, page_2 contains the remaining 2 segments from packet_1, and   page_3 contains the first three pages of packet_2.  Finally, this   logical bitstream is multiplexed into a physical Ogg bitstream with   pages of other logical bitstreams.6. The Ogg page format   A physical Ogg bitstream consists of a sequence of concatenated   pages.  Pages are of variable size, usually 4-8 kB, maximum 65307   bytes.  A page header contains all the information needed to   demultiplex the logical bitstreams out of the physical bitstream and   to perform basic error recovery and landmarks for seeking.  Each page   is a self-contained entity such that the page decode mechanism can   recognize, verify, and handle single pages at a time without   requiring the overall bitstream.   The Ogg page header 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| Byte+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| capture_pattern: Magic number for page start "OggS"           | 0-3+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| version       | header_type   | granule_position              | 4-7+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|                                                               | 8-11+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|                               | bitstream_serial_number       | 12-15+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|                               | page_sequence_number          | 16-19+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|                               | CRC_checksum                  | 20-23+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+|                               |page_segments  | segment_table | 24-27+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+| ...                                                           | 28-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   The LSb (least significant bit) comes first in the Bytes.  Fields   with more than one byte length are encoded LSB (least significant   byte) first.Pfeiffer                     Informational                      [Page 9]

RFC 3533                          OGG                           May 2003   The fields in the page header have the following meaning:   1. capture_pattern: a 4 Byte field that signifies the beginning of a      page.  It contains the magic numbers:            0x4f 'O'            0x67 'g'            0x67 'g'            0x53 'S'      It helps a decoder to find the page boundaries and regain      synchronisation after parsing a corrupted stream.  Once the      capture pattern is found, the decoder verifies page sync and      integrity by computing and comparing the checksum.   2. stream_structure_version: 1 Byte signifying the version number of      the Ogg file format used in this stream (this document specifies      version 0).   3. header_type_flag: the bits in this 1 Byte field identify the      specific type of this page.      *  bit 0x01         set: page contains data of a packet continued from the previous            page         unset: page contains a fresh packet      *  bit 0x02         set: this is the first page of a logical bitstream (bos)         unset: this page is not a first page      *  bit 0x04         set: this is the last page of a logical bitstream (eos)         unset: this page is not a last page   4. granule_position: an 8 Byte field containing position information.      For example, for an audio stream, it MAY contain the total number      of PCM samples encoded after including all frames finished on this      page.  For a video stream it MAY contain the total number of videoPfeiffer                     Informational                     [Page 10]

RFC 3533                          OGG                           May 2003      frames encoded after this page.  This is a hint for the decoder      and gives it some timing and position information.  Its meaning is      dependent on the codec for that logical bitstream and specified in      a specific media mapping.  A special value of -1 (in two's      complement) indicates that no packets finish on this page.   5. bitstream_serial_number: a 4 Byte field containing the unique      serial number by which the logical bitstream is identified.   6. page_sequence_number: a 4 Byte field containing the sequence      number of the page so the decoder can identify page loss.  This      sequence number is increasing on each logical bitstream      separately.   7. CRC_checksum: a 4 Byte field containing a 32 bit CRC checksum of      the page (including header with zero CRC field and page content).      The generator polynomial is 0x04c11db7.   8. number_page_segments: 1 Byte giving the number of segment entries      encoded in the segment table.   9. segment_table: number_page_segments Bytes containing the lacing      values of all segments in this page.  Each Byte contains one      lacing value.   The total header size in bytes is given by:   header_size = number_page_segments + 27 [Byte]   The total page size in Bytes is given by:   page_size = header_size + sum(lacing_values: 1..number_page_segments)   [Byte]7. Security Considerations   The Ogg encapsulation format is a container format and only   encapsulates content (such as Vorbis-encoded audio).  It does not   provide for any generic encryption or signing of itself or its   contained content bitstreams.  However, it encapsulates any kind of   content bitstream as long as there is a codec for it, and is thus   able to contain encrypted and signed content data.  It is also   possible to add an external security mechanism that encrypts or signs   an Ogg physical bitstream and thus provides content confidentiality   and authenticity.   As Ogg encapsulates binary data, it is possible to include executable   content in an Ogg bitstream.  This can be an issue with applications   that are implemented using the Ogg format, especially when Ogg is   used for streaming or file transfer in a networking scenario.  AsPfeiffer                     Informational                     [Page 11]

RFC 3533                          OGG                           May 2003   such, Ogg does not pose a threat there.  However, an application   decoding Ogg and its encapsulated content bitstreams has to ensure   correct handling of manipulated bitstreams, of buffer overflows and   the like.8. References   [1] Walleij, L., "The application/ogg Media Type",RFC 3534, May       2003.   [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement       Levels",BCP 14,RFC 2119, March 1997.Pfeiffer                     Informational                     [Page 12]

RFC 3533                          OGG                           May 2003Appendix A. Glossary of terms and abbreviations   bos page: The initial page (beginning of stream) of a logical      bitstream which contains information to identify the codec type      and other decoding-relevant information.   chaining (or sequential multiplexing): Concatenation of two or more      complete physical Ogg bitstreams.   eos page: The final page (end of stream) of a logical bitstream.   granule position: An increasing position number for a specific      logical bitstream stored in the page header.  Its meaning is      dependent on the codec for that logical bitstream and specified in      a specific media mapping.   grouping (or concurrent multiplexing): Interleaving of pages of      several logical bitstreams into one complete physical Ogg      bitstream under the restriction that all bos pages of all grouped      logical bitstreams MUST appear before any data pages.   lacing value: An entry in the segment table of a page header      representing the size of the related segment.   logical bitstream: A sequence of bits being the result of an encoded      media stream.   media mapping: A specific use of the Ogg encapsulation format      together with a specific (set of) codec(s).   (Ogg) packet: A subpart of a logical bitstream that is created by the      encoder for that bitstream and represents a meaningful entity for      the encoder, but only a sequence of bits to the Ogg encapsulation.   (Ogg) page: A physical bitstream consists of a sequence of Ogg pages      containing data of one logical bitstream only.  It usually      contains a group of contiguous segments of one packet only, but      sometimes packets are too large and need to be split over several      pages.   physical (Ogg) bitstream: The sequence of bits resulting from an Ogg      encapsulation of one or several logical bitstreams.  It consists      of a sequence of pages from the logical bitstreams with the      restriction that the pages of one logical bitstream MUST come in      their correct temporal order.Pfeiffer                     Informational                     [Page 13]

RFC 3533                          OGG                           May 2003   (Ogg) segment: The Ogg encapsulation process splits each packet into      chunks of 255 bytes plus a last fractional chunk of less than 255      bytes.  These chunks are called segments.Appendix B. Acknowledgements   The author gratefully acknowledges the work that Christopher   Montgomery  and the Xiph.Org foundation have done in defining the Ogg   multimedia project and as part of it the open file format described   in this document.  The author hopes that providing this document to   the Internet community will help in promoting the Ogg multimedia   project athttp://www.xiph.org/.  Many thanks also for the many   technical and typo corrections that C. Montgomery and the Ogg   community provided as feedback to this RFC.Author's Address   Silvia Pfeiffer   CSIRO, Australia   Locked Bag 17   North Ryde, NSW  2113   Australia   Phone: +61 2 9325 3141   EMail: Silvia.Pfeiffer@csiro.au   URI:http://www.cmis.csiro.au/Silvia.Pfeiffer/Pfeiffer                     Informational                     [Page 14]

RFC 3533                          OGG                           May 2003Full Copyright Statement   Copyright (C) The Internet Society (2003).  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.Pfeiffer                     Informational                     [Page 15]