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Network Working Group                                        A. MelnikovRequest for Comments: 4466                                    Isode Ltd.Updates:2088,2342,3501,3502,3516                           C. DabooCategory: Standards Track                                     April 2006Collected Extensions to IMAP4 ABNFStatus 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 (2006).Abstract   Over the years, many documents from IMAPEXT and LEMONADE working   groups, as well as many individual documents, have added syntactic   extensions to many base IMAP commands described inRFC 3501.  For   ease of reference, this document collects most of such ABNF changes   in one place.   This document also suggests a set of standard patterns for adding   options and extensions to several existing IMAP commands defined inRFC 3501.  The patterns provide for compatibility between existing   and future extensions.   This document updates ABNF in RFCs 2088, 2342, 3501, 3502, and 3516.   It also includes part of the errata toRFC 3501.  This document   doesn't specify any semantic changes to the listed RFCs.Melnikov & Daboo            Standards Track                     [Page 1]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006Table of Contents1. Introduction ....................................................21.1. Purpose of This Document ...................................21.2. Conventions Used in This Document ..........................32. IMAP ABNF Extensions ............................................32.1. Optional Parameters with the SELECT/EXAMINE Commands .......32.2. Extended CREATE Command ....................................42.3. Extended RENAME Command ....................................52.4. Extensions to FETCH and UID FETCH Commands .................62.5. Extensions to STORE and UID STORE Commands .................62.6. Extensions to SEARCH Command ...............................72.6.1. Extended SEARCH Command .............................72.6.2. ESEARCH untagged response ...........................82.7. Extensions to APPEND Command ...............................83. Formal Syntax ...................................................94. Security Considerations ........................................145. Normative References ...........................................156. Acknowledgements ...............................................151.  Introduction1.1.  Purpose of This Document   This document serves several purposes:      1.  rationalize and generalize ABNF for some existing IMAP          extensions;      2.  collect the ABNF in one place in order to minimize cross          references between documents;      3.  define building blocks for future extensions so that they can          be used together in a compatible way.   It is expected that a future revision of this document will be   incorporated into a revision ofRFC 3501.   This document updates ABNF in RFCs 2088, 2342, 3501, 3502, and 3516.   It also includes part of the errata toRFC 3501.  This document   doesn't specify any semantic changes to the listed RFCs.   The ABNF insection 6 of RFC 2342 got rewritten to conform to the   ABNF syntax as defined inRFC 4234 and to reference new non-terminals   fromRFC 3501.  It was also restructured to allow for better   readability.  There were no changes "on the wire".Section 2 extends ABNF for SELECT, EXAMINE, CREATE, RENAME, FETCH/UID   FETCH, STORE/UID STORE, SEARCH, and APPEND commands in a consistent   manner.  Extensions to all the commands but APPEND have the sameMelnikov & Daboo            Standards Track                     [Page 2]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006   structure.  Extensibility for the APPEND command was done slightly   differently in order to preserve backward compatibility with existing   extensions.Section 2 also defines a new ESEARCH response, whose purpose is to   define a better version of the SEARCH response defined inRFC 3501.Section 3 defines the collected ABNF that replaces pieces of ABNF in   the aforementioned RFCs.  The collected ABNF got generalized to allow   for easier future extensibility.1.2.  Conventions Used in This Document   In examples, "C:" and "S:" indicate lines sent by the client and   server, respectively.   The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"   in this document are to be interpreted as defined in "Key words for   use in RFCs to Indicate Requirement Levels" [KEYWORDS].2.  IMAP ABNF Extensions   This section is not normative.  It provides some background on the   intended use of different extensions and it gives some guidance about   how future extensions should extend the described commands.2.1.  Optional Parameters with the SELECT/EXAMINE Commands   This document adds the ability to include one or more parameters with   the IMAP SELECT (section 6.3.1 of [IMAP4]) or EXAMINE (section 6.3.2   of [IMAP4]) commands, to turn on or off certain standard behaviors,   or to add new optional behaviors required for a particular extension.   There are two possible modes of operation:   o  A global state change where a single use of the optional parameter      will affect the session state from that time on, irrespective of      subsequent SELECT/EXAMINE commands.   o  A per-mailbox state change that will affect the session only for      the duration of the new selected state.  A subsequent      SELECT/EXAMINE without the optional parameter will cancel its      effect for the newly selected mailbox.   Optional parameters to the SELECT or EXAMINE commands are added as a   parenthesized list of attribute/value pairs, and appear after the   mailbox name in the standard SELECT or EXAMINE command.  The order of   individual parameters is arbitrary.  A parameter value is optionalMelnikov & Daboo            Standards Track                     [Page 3]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006   and may consist of atoms, strings, or lists in a specific order.  If   the parameter value is present, it always appears in parentheses (*).   Any parameter not defined by extensions that the server supports must   be rejected with a BAD response.      Example:              C: a SELECT INBOX (ANNOTATE)              S: ...              S: a OK SELECT complete      In the above example, a single parameter is used with the SELECT      command.      Example:              C: a EXAMINE INBOX (ANNOTATE RESPONSES ("UID Responses")                 CONDSTORE)              S: ...              S: a OK EXAMINE complete      In the above example, three parameters are used with the EXAMINE      command.  The second parameter consists of two items: an atom      "RESPONSES" followed by a quoted string.      Example:              C: a SELECT INBOX (BLURDYBLOOP)              S: a BAD Unknown parameter in SELECT command      In the above example, a parameter not supported by the server is      used.  This results in the BAD response from the server.   (*) - if a parameter has a mandatory value, which can always be   represented as a number or a sequence-set, the parameter value does   not need the enclosing ().  See ABNF for more details.2.2.  Extended CREATE Command   Arguments:  mailbox name               OPTIONAL list of CREATE parameters   Responses:  no specific responses for this command   Result:     OK - create completed               NO - create failure: cannot create mailbox with                    that name               BAD - argument(s) invalidMelnikov & Daboo            Standards Track                     [Page 4]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006   This document adds the ability to include one or more parameters with   the IMAP CREATE command (see section 6.3.3 of [IMAP4]), to turn on or   off certain standard behaviors, or to add new optional behaviors   required for a particular extension.  No CREATE parameters are   defined in this document.   Optional parameters to the CREATE command are added as a   parenthesized list of attribute/value pairs after the mailbox name.   The order of individual parameters is arbitrary.  A parameter value   is optional and may consist of atoms, strings, or lists in a specific   order.  If the parameter value is present, it always appears in   parentheses (*).  Any parameter not defined by extensions that the   server supports must be rejected with a BAD response.   (*) - if a parameter has a mandatory value, which can always be   represented as a number or a sequence-set, the parameter value does   not need the enclosing ().  See ABNF for more details.2.3.  Extended RENAME Command   Arguments:  existing mailbox name               new mailbox name               OPTIONAL list of RENAME parameters   Responses:  no specific responses for this command   Result:     OK - rename completed               NO - rename failure: cannot rename mailbox with                    that name, cannot rename to mailbox with                    that name, etc.               BAD - argument(s) invalid   This document adds the ability to include one or more parameters with   the IMAP RENAME command (see section 6.3.5 of [IMAP4]), to turn on or   off certain standard behaviors, or to add new optional behaviors   required for a particular extension.  No RENAME parameters are   defined in this document.   Optional parameters to the RENAME command are added as a   parenthesized list of attribute/value pairs after the new mailbox   name.  The order of individual parameters is arbitrary.  A parameter   value is optional and may consist of atoms, strings, or lists in a   specific order.  If the parameter value is present, it always appears   in parentheses (*).  Any parameter not defined by extensions that the   server supports must be rejected with a BAD response.Melnikov & Daboo            Standards Track                     [Page 5]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006   (*) - if a parameter has a mandatory value, which can always be   represented as a number or a sequence-set, the parameter value does   not need the enclosing ().  See ABNF for more details.2.4.  Extensions to FETCH and UID FETCH Commands   Arguments:  sequence set               message data item names or macro               OPTIONAL fetch modifiers   Responses:  untagged responses: FETCH   Result:     OK - fetch completed               NO - fetch error: cannot fetch that data               BAD - command unknown or arguments invalid   This document extends the syntax of the FETCH and UID FETCH commands   (see section 6.4.5 of [IMAP4]) to include optional FETCH modifiers.   No fetch modifiers are defined in this document.   The order of individual modifiers is arbitrary.  Each modifier is an   attribute/value pair.  A modifier value is optional and may consist   of atoms and/or strings and/or lists in a specific order.  If the   modifier value is present, it always appears in parentheses (*).  Any   modifiers not defined by extensions that the server supports must be   rejected with a BAD response.   (*) - if a modifier has a mandatory value, which can always be   represented as a number or a sequence-set, the modifier value does   not need the enclosing ().  See ABNF for more details.2.5.  Extensions to STORE and UID STORE Commands   Arguments:  message set               OPTIONAL store modifiers               message data item name               value for message data item   Responses:  untagged responses: FETCH   Result:     OK - store completed               NO - store error: cannot store that data               BAD - command unknown or arguments invalid   This document extends the syntax of the STORE and UID STORE commands   (see section 6.4.6 of [IMAP4]) to include optional STORE modifiers.   No store modifiers are defined in this document.Melnikov & Daboo            Standards Track                     [Page 6]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006   The order of individual modifiers is arbitrary.  Each modifier is an   attribute/value pair.  A modifier value is optional and may consist   of atoms and/or strings and/or lists in a specific order.  If the   modifier value is present, it always appears in parentheses (*).  Any   modifiers not defined by extensions that the server supports must be   rejected with a BAD response.   (*) - if a modifier has a mandatory value, which can always be   represented as a number or a sequence-set, the modifier value does   not need the enclosing ().  See ABNF for more details.2.6.  Extensions to SEARCH Command2.6.1.  Extended SEARCH Command   Arguments:  OPTIONAL result specifier               OPTIONAL [CHARSET] specification               searching criteria (one or more)   Responses:  REQUIRED untagged response: SEARCH (*)   Result:     OK - search completed               NO - search error: cannot search that [CHARSET] or                    criteria               BAD - command unknown or arguments invalid   This section updates definition of the SEARCH command described in   section 6.4.4 of [IMAP4].   The SEARCH command is extended to allow for result options.  This   document does not define any result options.   The order of individual options is arbitrary.  Individual options may   contain parameters enclosed in parentheses (**).  If an option has   parameters, they consist of atoms and/or strings and/or lists in a   specific order.  Any options not defined by extensions that the   server supports must be rejected with a BAD response.   (*) - An extension to the SEARCH command may require another untagged   response, or no untagged response to be returned.Section 2.6.2   defines a new ESEARCH untagged response that replaces the SEARCH   untagged response.  Note that for a given extended SEARCH command the   SEARCH and ESEARCH responses SHOULD be mutually exclusive, i.e., only   one of them should be returned.   (**) - if an option has a mandatory parameter, which can always be   represented as a number or a sequence-set, the option parameter does   not need the enclosing ().  See ABNF for more details.Melnikov & Daboo            Standards Track                     [Page 7]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 20062.6.2.  ESEARCH untagged response   Contents:   one or more search-return-data pairs   The ESEARCH response SHOULD be sent as a result of an extended SEARCH   or UID SEARCH command specified insection 2.6.1.   The ESEARCH response starts with an optional search correlator.  If   it is missing, then the response was not caused by a particular IMAP   command, whereas if it is present, it contains the tag of the command   that caused the response to be returned.   The search correlator is followed by an optional UID indicator.  If   this indicator is present, all data in the ESEARCH response refers to   UIDs, otherwise all returned data refers to message numbers.   The rest of the ESEARCH response contains one or more search data   pairs.  Each pair starts with unique return item name, followed by a   space and the corresponding data.  Search data pairs may be returned   in any order.  Unless specified otherwise by an extension, any return   item name SHOULD appear only once in an ESEARCH response.   Example:    S: * ESEARCH UID COUNT 5 ALL 4:19,21,28   Example:    S: * ESEARCH (TAG "a567") UID COUNT 5 ALL 4:19,21,28   Example:    S: * ESEARCH COUNT 5 ALL 1:17,212.7.  Extensions to APPEND Command   The IMAP BINARY extension [BINARY] extends the APPEND command to   allow a client to append data containing NULs by using the <literal8>   syntax.  The ABNF was rewritten to allow for easier extensibility by   IMAP extensions.  This document hasn't specified any semantical   changes to the [BINARY] extension.   In addition, the non-terminal "literal8" defined in [BINARY] got   extended to allow for non-synchronizing literals if both [BINARY] and   [LITERAL+] extensions are supported by the server.   The IMAP MULTIAPPEND extension [MULTIAPPEND] extends the APPEND   command to allow a client to append multiple messages atomically.   This document defines a common syntax for the APPEND command that   takes into consideration syntactic extensions defined by both   [BINARY] and [MULTIAPPEND] extensions.Melnikov & Daboo            Standards Track                     [Page 8]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 20063.  Formal Syntax   The following syntax specification uses the Augmented Backus-Naur   Form (ABNF) notation as specified in [ABNF].   Non-terminals referenced but not defined below are as defined by   [IMAP4].   Except as noted otherwise, all alphabetic characters are case-   insensitive.  The use of uppercase or lowercase characters to define   token strings is for editorial clarity only.  Implementations MUST   accept these strings in a case-insensitive fashion.   append          = "APPEND" SP mailbox 1*append-message                     ;; only a single append-message may appear                     ;; if MULTIAPPEND [MULTIAPPEND] capability                     ;; is not present   append-message  = append-opts SP append-data   append-ext      = append-ext-name SP append-ext-value                     ;; This non-terminal define extensions to                     ;; to message metadata.   append-ext-name = tagged-ext-label   append-ext-value= tagged-ext-val                     ;; This non-terminal shows recommended syntax                     ;; for future extensions.   append-data     = literal / literal8 / append-data-ext   append-data-ext = tagged-ext                     ;; This non-terminal shows recommended syntax                     ;; for future extensions,                     ;; i.e., a mandatory label followed                     ;; by parameters.   append-opts     = [SP flag-list] [SP date-time] *(SP append-ext)                     ;; message metadata   charset         = atom / quoted                     ;; Exact syntax is defined in [CHARSET].   create          = "CREATE" SP mailbox                     [create-params]                     ;; Use of INBOX gives a NO error.Melnikov & Daboo            Standards Track                     [Page 9]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006   create-params   = SP "(" create-param *( SP create-param) ")"   create-param-name = tagged-ext-label   create-param      = create-param-name [SP create-param-value]   create-param-value= tagged-ext-val                     ;; This non-terminal shows recommended syntax                     ;; for future extensions.   esearch-response  = "ESEARCH" [search-correlator] [SP "UID"]                        *(SP search-return-data)                      ;; Note that SEARCH and ESEARCH responses                      ;; SHOULD be mutually exclusive,                      ;; i.e., only one of the response types                      ;; should be                      ;; returned as a result of a command.   examine         = "EXAMINE" SP mailbox [select-params]                     ;; modifies the original IMAP EXAMINE command                     ;; to accept optional parameters   fetch           = "FETCH" SP sequence-set SP ("ALL" / "FULL" /                     "FAST" / fetch-att /                     "(" fetch-att *(SP fetch-att) ")")                     [fetch-modifiers]                     ;; modifies the original IMAP4 FETCH command to                     ;; accept optional modifiers   fetch-modifiers = SP "(" fetch-modifier *(SP fetch-modifier) ")"   fetch-modifier  = fetch-modifier-name [ SP fetch-modif-params ]   fetch-modif-params  = tagged-ext-val                     ;; This non-terminal shows recommended syntax                     ;; for future extensions.   fetch-modifier-name = tagged-ext-label   literal8        = "~{" number ["+"] "}" CRLF *OCTET                      ;; A string that might contain NULs.                      ;; <number> represents the number of OCTETs                      ;; in the response string.                      ;; The "+" is only allowed when both LITERAL+ and                      ;; BINARY extensions are supported by the server.Melnikov & Daboo            Standards Track                    [Page 10]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006   mailbox-data      =/ Namespace-Response /                        esearch-response   Namespace         = nil / "(" 1*Namespace-Descr ")"   Namespace-Command = "NAMESPACE"   Namespace-Descr   = "(" string SP                          (DQUOTE QUOTED-CHAR DQUOTE / nil)                           *(Namespace-Response-Extension) ")"   Namespace-Response-Extension = SP string SP                     "(" string *(SP string) ")"   Namespace-Response = "NAMESPACE" SP Namespace                        SP Namespace SP Namespace         ;; This response is currently only allowed         ;; if the IMAP server supports [NAMESPACE].         ;; The first Namespace is the Personal Namespace(s)         ;; The second Namespace is the Other Users' Namespace(s)         ;; The third Namespace is the Shared Namespace(s)   rename          = "RENAME" SP mailbox SP mailbox                     [rename-params]                     ;; Use of INBOX as a destination gives                     ;; a NO error, unless rename-params                     ;; is not empty.   rename-params     = SP "(" rename-param *( SP rename-param) ")"   rename-param      = rename-param-name [SP rename-param-value]   rename-param-name = tagged-ext-label   rename-param-value= tagged-ext-val                     ;; This non-terminal shows recommended syntax                     ;; for future extensions.   response-data   = "*" SP response-payload CRLF   response-payload= resp-cond-state / resp-cond-bye /                     mailbox-data / message-data / capability-data   search          = "SEARCH" [search-return-opts]                     SP search-program   search-correlator  = SP "(" "TAG" SP tag-string ")"Melnikov & Daboo            Standards Track                    [Page 11]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006   search-program     = ["CHARSET" SP charset SP]                        search-key *(SP search-key)                        ;; CHARSET argument to SEARCH MUST be                        ;; registered with IANA.   search-return-data = search-modifier-name SP search-return-value                        ;; Note that not every SEARCH return option                        ;; is required to have the corresponding                        ;; ESEARCH return data.   search-return-opts = SP "RETURN" SP "(" [search-return-opt                        *(SP search-return-opt)] ")"   search-return-opt = search-modifier-name [SP search-mod-params]   search-return-value = tagged-ext-val                        ;; Data for the returned search option.                        ;; A single "nz-number"/"number" value                        ;; can be returned as an atom (i.e., without                        ;; quoting).  A sequence-set can be returned                        ;; as an atom as well.   search-modifier-name = tagged-ext-label   search-mod-params = tagged-ext-val                     ;; This non-terminal shows recommended syntax                     ;; for future extensions.   select          = "SELECT" SP mailbox [select-params]                     ;; modifies the original IMAP SELECT command to                     ;; accept optional parameters   select-params   = SP "(" select-param *(SP select-param) ")"   select-param    = select-param-name [SP select-param-value]                     ;; a parameter to SELECT may contain one or                     ;; more atoms and/or strings and/or lists.   select-param-name= tagged-ext-label   select-param-value= tagged-ext-val                     ;; This non-terminal shows recommended syntax                     ;; for future extensions.   status-att-list = status-att-val *(SP status-att-val)                     ;; Redefines status-att-list fromRFC 3501.Melnikov & Daboo            Standards Track                    [Page 12]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006                     ;; status-att-val is defined inRFC 3501 errata   status-att-val  = ("MESSAGES" SP number) /                     ("RECENT" SP number) /                     ("UIDNEXT" SP nz-number) /                     ("UIDVALIDITY" SP nz-number) /                     ("UNSEEN" SP number)                     ;; Extensions to the STATUS responses                     ;; should extend this production.                     ;; Extensions should use the generic                     ;; syntax defined by tagged-ext.   store           = "STORE" SP sequence-set [store-modifiers]                     SP store-att-flags                     ;; extend [IMAP4] STORE command syntax                     ;; to allow for optional store-modifiers   store-modifiers =  SP "(" store-modifier *(SP store-modifier)                       ")"   store-modifier  = store-modifier-name [SP store-modif-params]   store-modif-params = tagged-ext-val                     ;; This non-terminal shows recommended syntax                     ;; for future extensions.   store-modifier-name = tagged-ext-label   tag-string         = string                        ;; tag of the command that caused                        ;; the ESEARCH response, sent as                        ;; a string.   tagged-ext          = tagged-ext-label SP tagged-ext-val                          ;; recommended overarching syntax for                          ;; extensions   tagged-ext-label    = tagged-label-fchar *tagged-label-char                         ;; Is a validRFC 3501 "atom".   tagged-label-fchar  = ALPHA / "-" / "_" / "."   tagged-label-char   = tagged-label-fchar / DIGIT / ":"Melnikov & Daboo            Standards Track                    [Page 13]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006   tagged-ext-comp     = astring /                         tagged-ext-comp *(SP tagged-ext-comp) /                         "(" tagged-ext-comp ")"                          ;; Extensions that follow this general                          ;; syntax should use nstring instead of                          ;; astring when appropriate in the context                          ;; of the extension.                          ;; Note that a message set or a "number"                          ;; can always be represented as an "atom".                          ;; An URL should be represented as                          ;; a "quoted" string.   tagged-ext-simple   = sequence-set / number   tagged-ext-val      = tagged-ext-simple /                         "(" [tagged-ext-comp] ")"4.  Security Considerations   This document updates ABNF in RFCs 2088, 2342, 3501, 3502, and 3516.   The updated documents must be consulted for security considerations   for the extensions that they define.   As a protocol gets more complex, parser bugs become more common   including buffer overflow, denial of service, and other common   security coding errors.  To the extent that this document makes the   parser more complex, it makes this situation worse.  To the extent   that this document makes the parser more consistent and thus simpler,   the situation is improved.  The impact will depend on how many   deployed IMAP extensions are consistent with this document.   Implementers are encouraged to take care of these issues when   extending existing implementations.  Future IMAP extensions should   strive for consistency and simplicity to the greatest extent   possible.   Extensions to IMAP commands that are permitted in NOT AUTHENTICATED   state are more sensitive to these security issues due to the larger   possible attacker community prior to authentication, and the fact   that some IMAP servers run with elevated privileges in that state.   This document does not extend any commands permitted in NOT   AUTHENTICATED state.  Future IMAP extensions to commands permitted in   NOT AUTHENTICATED state should favor simplicity over consistency or   extensibility.Melnikov & Daboo            Standards Track                    [Page 14]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 20065.  Normative References   [KEYWORDS]    Bradner, S., "Key words for use in RFCs to Indicate                 Requirement Levels",BCP 14,RFC 2119, March 1997.   [IMAP4]       Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL -                 VERSION 4rev1",RFC 3501, March 2003.   [ABNF]        Crocker, D., Ed., and P. Overell, "Augmented BNF for                 Syntax Specifications: ABNF",RFC 4234, October 2005.   [CHARSET]     Freed, N. and J. Postel, "IANA Charset Registration                 Procedures",BCP 19,RFC 2978, October 2000.   [MULTIAPPEND] Crispin, M., "Internet Message Access Protocol (IMAP) -                 MULTIAPPEND Extension",RFC 3502, March 2003.   [NAMESPACE]   Gahrns, M. and C. Newman, "IMAP4 Namespace",RFC 2342,                 May 1998.   [LITERAL+]    Myers, J., "IMAP4 non-synchronizing literals",RFC2088, January 1997.   [BINARY]      Nerenberg, L., "IMAP4 Binary Content Extension",RFC3516, April 2003.6.  Acknowledgements   This documents is based on ideas proposed by Pete Resnick, Mark   Crispin, Ken Murchison, Philip Guenther, Randall Gellens, and Lyndon   Nerenberg.   However, all errors and omissions must be attributed to the authors   of the document.   Thanks to Philip Guenther, Dave Cridland, Mark Crispin, Chris Newman,   Elwyn Davies, and Barry Leiba for comments and corrections.   literal8 syntax was taken fromRFC 3516.Melnikov & Daboo            Standards Track                    [Page 15]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006Authors' Addresses   Alexey Melnikov   Isode Limited   5 Castle Business Village   36 Station Road   Hampton, Middlesex, TW12 2BX   UK   EMail: Alexey.Melnikov@isode.com   Cyrus Daboo   EMail: cyrus@daboo.nameMelnikov & Daboo            Standards Track                    [Page 16]

RFC 4466           Collected Extensions to IMAP4 ABNF         April 2006Full Copyright Statement   Copyright (C) The Internet Society (2006).   This document is subject to the rights, licenses and restrictions   contained inBCP 78, and except as set forth therein, the authors   retain all their rights.   This document and the information contained herein are provided on an   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET   ENGINEERING TASK FORCE DISCLAIM 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.Intellectual Property   The IETF takes no position regarding the validity or scope of any   Intellectual Property Rights or other rights that might be claimed to   pertain to the implementation or use of the technology described in   this document or the extent to which any license under such rights   might or might not be available; nor does it represent that it has   made any independent effort to identify any such rights.  Information   on the procedures with respect to rights in RFC documents can be   found inBCP 78 andBCP 79.   Copies of IPR disclosures made to the IETF Secretariat and any   assurances of licenses to be made available, or the result of an   attempt made to obtain a general license or permission for the use of   such proprietary rights by implementers or users of this   specification can be obtained from the IETF on-line IPR repository athttp://www.ietf.org/ipr.   The IETF invites any interested party to bring to its attention any   copyrights, patents or patent applications, or other proprietary   rights that may cover technology that may be required to implement   this standard.  Please address the information to the IETF at   ietf-ipr@ietf.org.Acknowledgement   Funding for the RFC Editor function is provided by the IETF   Administrative Support Activity (IASA).Melnikov & Daboo            Standards Track                    [Page 17]