IETF Fax Working Group Vivian Cancio Internet Draft Xerox Corporation Category: Work-in-progress Mike Moldovan Intended Category: Informational G3Nova Technology, Inc. Hiroshi Tamura Ricoh Company, LTD. Dan Wing Cisco Systems 31 October 2000 Expires: April 2001 Implementers Guide for Facsimile Using Internet Mail Status of this memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC 2026. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. [[INTENDED STATUS: 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 2000. All Rights Reserved. Abstract This document is intended for the implementers of software which uses email to send to facsimiles using RFC 2305 and 2532. This is an informational document and its guidelines do not supersede the referenced documents. Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 1] Internet draft Implementers Guide 31 October 2000 Table of contents 1. Introduction 1.1 Organization of this document 1.2 Discussion of this document 2. Terminology 3. Implementation Issues Specific to Simple Mode 3.1 Simple Mode Fax Senders 3.1.1 Multipart-alternative 3.2 Simple Mode Fax Receivers 3.2.1 Multipart-alternative and Storage Capacity 4. Implementation Issues Specific to Extended Mode 4.1 Multipart-alternative 4.2 Correlation of MDN with Original Message 4.3 Correlation of DSN with Original Message 4.4 Extended Mode Receivers 4.4.1 Confirmation of receipt and processing from UA Clients 4.4.1.1 Discrepancies in MDN [9] Interpretation 4.4.1.2 Disposition-Type: "dispatched" 4.4.1.3 "Subject" of MDN in Success and Failure Cases 4.4.1.4 "Body" of MDN in Success and Failure Cases 4.4.2 Extended Mode Receivers that are MTAs (or ESMTP servers) 4.4.2.1 Success Case Example 4.4.2.2 Failure Case Example 1 4.4.2.3 Failure Case Example 2 4.4.3 Extended Mode Receivers that are POP3/IMAP4 4.4.3.1 Success Case Example 4.4.3.2 Failure Case Example 4.4.4 Receiving Multiple TIFF-FX Attachments 5. Implementation Issues the File Format 5.1 IFD Placement in TIFF file & Profile-S Constraints 5.2 Precautions for implementers of RFC 2301 [4] 5.2.1 IFD Entry Errors 5.2.2 Strip Errors 5.2.3 Image Errors 5.2.4 Profile Specific Errors 6. Implementation Issues for Internet Fax Addressing 7. Security considerations 8. Acknowledgements 9. References 10. Authors' addresses Full copyright statement Revision history Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 2] Internet draft Implementers Guide 31 October 2000 1. Introduction This document clarifies published RFCs which standardize facsimile communications using Internet Email. The intent is to prevent implementations that deviate in such a way as to cause interoperability problems. 1.1 Organization of this document See Section 2 for terminology. a) Simple mode clarifications b) Extended mode clarifications c) File format clarifications d) Fax Addressing Clarifications e) Open implementation issues 1.2 Discussion of this document Discussion of this document should take place on the Internet fax mailing list hosted by the Internet Mail Consortium (IMC). Please send comments regarding this document to: ietf-fax@imc.org To subscribe to this list, send a message with the body 'subscribe' to "ietf-fax-request@imc.org". To see what has gone on before you subscribed, please see the mailing list archive at: http://www.imc.org/ietf-fax/ 2. Terminology The following terms are used throughout this document: DSN - RFC 1894 "An Extensible Message Format for Delivery Status Notifications" [7] Extended Mode - RFC 2532, "Extended Facsimile Using Internet Mail" [3] MDN - RFC 2298 "An Extensible Message Format for Message Disposition Notifications" [9] Simple Mode - RFC 2305, "A Simple Mode of Facsimile Using Internet Mail" [2] TIFF-FX - RFC 2301, "File Format for Internet Fax" [4] In examples, "C:" is used to indicates lines sent by the client, and "S:" to indicate those sent by the server. Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 3] Internet draft Implementers Guide 31 October 2000 3. Implementation Issues Specific to Simple Mode Issues specific to Simple Mode [2] are described below: 3.1 Simple Mode Fax Senders 3.1.1 Multipart/alternative Although a requirement of MIME compliance (16, Section 5.1.4), some email client implementations are not capable of correctly processing messages with a MIME Content-Type of "multipart/alternative". If a sender is unsure if the recipient is able to correctly process a message with a Content-Type of "multipart/alternative", the sender should assume the worst and not use this MIME Content-Type. 3.2 Simple Mode Fax Receivers 3.2.1 Multipart/alternative and Storage Capacity Devices with little storage capacity are unable to cache previous parts of a multipart/alternative message. In order for such devices to correctly process only one part of a multipart/alternative message, such devices may simply use the first process-able part of a multipart/alternative message. This is viable because the parts within a multipart/alternative are always sent in least- fidelity to most-fidelity order [16, Section 5.1.4]. This behavior means that even if subsequent, higher-fidelity parts may have been process-able they will not be used. This behavior can cause user dissatisfaction because when two high-fidelity but low-memory devices are used with each other, the lowest-fidelity part of the multipart/alternative will be processed. The solution to this problem is for the sender to determine the capability of the recipient and send only high fidelity. However a mechanism to determine the recipient capabilities prior to an initial message sent to the recipient doesn't yet exist on the Internet. After an initial message is sent, the Extended Mode mechanism described in RFC 2532 [3], Section 3.3 enables a recipient to include its capabilities in a delivery and/or a disposition notification: in a DSN if the recipient device is an RFC 2532/ESMTP [3] compliant server or in an MDN if the recipient is a User Agent. Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 4] Internet draft Implementers Guide 31 October 2000 4. Implementation Issues Specific to Extended Mode Issues specific to Extended Mode [3] fax are described below. Note that any Extended Mode device also needs to consider issues specific to Simple Mode as well (Section 3 of this document). 4.1 Multipart/Alternative Sections 3.1.1 and 3.2.1 are also applicable to this mode. 4.2. Correlation of MDN with Original Message To re-iterate a paragraph from section 2.1, RFC 2298 [9], it is included here: A message that contains a Disposition-Notification-To header SHOULD also contain a Message-ID header as specified in RFC 822 [10]. This will permit automatic correlation of MDNs with original messages by user agents. 4.3 Correlation of DSN with Original Message Similar to the requirement to correlate an MDN, above, DSNs also need to be correlated. This is best done using the ENVID parameter in the "MAIL" command. See Sections 3 and 5.4 of RFC 1891 [5] for details. 4.4 Extended Mode Receivers Confirmation that the facsimile image (TIFF-FX attachment) was delivered and successfully processed is an important aspect of the extended mode of facsimile using Internet mail. This section describes implementation issues with several types of confirmations. 4.4.1 Confirmation of receipt and processing from User Agents When a message is received with the "Disposition-Notification-To" header and the receiver has determined if the message is process-able, it may generate a: a) Negative MDN in case of error, or b) Positive MDN in case of success but note that to send an MDN, the sender must have included the "Disposition- Notification-To" header in the original message. The advantage of receiving a requested MDN acknowledgement from an Extended Mode recipient is the indication of success or failure to process the TIFF-FX file attachment that was sent. The attachment constitutes the facsimile message and not the body-content of the message. Therefore an Extended Mode sender would expect, and it is recommended that the Extended Mode receiver will acknowledge (with an MDN) the success or failure to decode and process the TIFF file attachment. Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 5] Internet draft Implementers Guide 31 October 2000 Implementers of the Extended Mode [3] should provide consistency in the feedback provided to senders in the form of error codes and/or failure/successful messages. 4.4.1.1 Discrepancies in MDN [9] Interpretation An Extended Mode sender must be aware that RFC 2298 [9] does not distinguish between the success or failure to decode the body-content part of the message and the success or failure to decode a file attachment. Consequently MDNs may be received which do not reflect the success or failure to decode the attached TIFF-FX file, but rather to decode the body-content part of the message. 4.4.1.2 Disposition-Type: "dispatched". If the receiver of an MDN request, is an RFC 2532 compliant device that automatically prints the received Internet mail messages and attachments, or forwards the attachment via GSTN fax, it should, in the case of success: a) Use "disposition-type" of "dispatched" (with no "disposition-modifier") in the MDN, and b) Use the text similar to the following in the body of the message: "This is a Return Receipt for the mail that you sent to [above, or below, or here address, etc]. The message and attached files[s] may have been printed, faxed or saved. This is no guarantee that the message has been read or understood". and in the case of failure: a) Use "disposition-type" of "processed" and disposition-modifier of "error", and b) Use text similar to the following in the body of the message: "This is a Return Receipt for the mail that you sent to [above, or below, or here address, etc]. An error occurred while attempting to decode the attached file[s]". This recommendation adheres to the definition in RFC 2298 [9] and helps to distinguish the returned MDNs for proper handling. Implementers may wish to consider sending messages in the language of the sender (by utilizing a header field from the original message) or including multiple languages by using multipart/alternative for the text portion of the MDN. Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 6] Internet draft Implementers Guide 31 October 2000 4.4.1.3 "Subject" of MDN in Success and Failure Cases Because legacy e-mail applications do not parse the machine-readable headers, e- mail users depend on the human-readable parts of the MDN to recognize the type of acknowledgement that is received. For the sake of consistency and to help users visually distinguish a DSN from an MDN returned notification, it is suggested that the text 'disposition' be used for MDNs in the 'Subject' field. Examples: Subject: Disposition Notification (MDN) - Success Subject: Disposition Notification (MDN) û Failure Subject: Delivery Status Notification (DSN) û Success Subject: Delivery Status Notification (DSN) û Failure 4.4.2 Extended Mode Receivers that are MTAs (or ESMTP servers) It is strongly encouraged that SMTP server-based implementations should implement "SMTP Service Extension for Returning Enhanced Error Codes" [6]. This standard is easy to implement and it allows detailed standardized success and error indications to be returned to the sender by the submitting MTA. The following examples are provided as illustration only. They should not be interpreted as limiting the protocol or the DSN form. If the examples conflict with the definitions in the standards (RFC 1891/1893/1894/2034), the standards take precedence. 4.4.2.1 Success Case Example In the following example the sender sends a message to receiver which is an ESMTP server and the receiver successfully decodes the message. water.line.com +-------+ | Mail | | User | | Agent | +-------+ | V +----------+ +--------+ +---------+ | Mail + | Mail | | Mail | |Submission|----->|Transfer|---->|Transfer | | Agent | | Agent | | Agent | +----------+ +--------+ +---------+ foo.com copper.point.com Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 7] Internet draft Implementers Guide 31 October 2000 SMTP Sequence: S: 220 copper.point.com SMTP service ready C: EHLO water.line.com S: 250-copper.point.com S: 250-DSN S: 250 ENHANCEDSTATUSCODES C: MAIL FROM: RET=HDRS ENVID=MM123456 S: 250 2.1.0 Originator ok C: RCPT TO: NOTIFY=SUCCESS,FAILURE ORCPT=rfc822; ifax@copper.point.com S: 250 2.1.5 Recipient ok C: DATA S: 354 Send message, ending in . S: Date: 1 June 1999 12:00:00 û0700 S: MIME-Version: 1.0 S: Content-Type: Image/Tiff S: Content-Transfer-Encoding: Base64 S: From: Jean S: To: IFax Message Holder S: Message-ID: <12345@water.line.com> S: S: JEKFEJFKEJKFEJKFJKEJFKEJEJKFEJFKJEKFEE S: EJFJEKFJEKFJEKJFEKJFKEJFKEFJEKFJKEJFKE S: . . . S: EJFKEJFKEJFKEJFKJEKFJEKJFKEJFKEKEFJKEJFE S: EJFKEJFKEJFKEJFKEKFJEKFJEKJFKEJFKEJFKEJF S: . S: 250 2.0.0 Message accepted C: QUIT S: 221 2.0.0 Goodbye Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 8] Internet draft Implementers Guide 31 October 2000 DSN (to jean@water.line.com): Date: Mon, 12 Dec 1999 19:01:57 +0900 From: postmaster@copper.point.com Message-ID: <19991212190157.01234@copper.point.com> To: jean@water.line.com Subject: Delivery Notification (DSN) - Success MIME-Version: 1.0 Content-Type: multipart/report; report-type=delivery-status; boundary=JUK199912121854870001 --JUK199912121854870001 Content-type: text/plain Your message (id MM123456) was successfully delivered to ifax@copper.point.com. --JUK199912121854870001 Content-type: message/delivery-status Reporting-MTA: dns; copper.point.com Original-Envelope-ID: MM123456 Final-Recipient: rfc822;ifax@copper.point.com Action: delivered Status: 2.1.5 (Destination address valid) Diagnostic-Code: smtp; 250 2.1.5 Recipient ok --JUK199912121854870001 Content-type: message/rfc822-headers Date: 1 June 1999 12:00:00 -0700 MIME-Version: 1.0 Content-Type: Image/Tiff Content-Transfer-Encoding: Base64 From: Jean To: IFax Message Holder Message-ID: <12345@water.line.com> --JUK199912121854870001-- Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 9] Internet draft Implementers Guide 31 October 2000 4.4.2.2 Failure Case Example 1 In this example the receiver determines it is unable to decode the attached TIFF file AFTER it has received the SMTP message. The receiver then sends a 'failure' DSN. water.line.com +-------+ | Mail | | User | | Agent | +-------+ | V +----------+ +--------+ +---------+ | Mail + | Mail | | Mail | |Submission|----->|Transfer|---->|Transfer | | Agent | | Agent | | Agent | +----------+ +--------+ +---------+ foo.com copper.point.com SMTP Sequence: This is the same as the case a). After the sequence, a decode error occurs at the receiver, so instead of a 'success' DSN, a 'failure' DSN is sent. Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 10] Internet draft Implementers Guide 31 October 2000 DSN (to jean@water.line.com): Date: Mon, 12 Dec 1999 19:31:20 +0900 From: postmaster@copper.point.com Message-ID: <19991212193120.87652@copper.point.com> To: jean@water.line.com Subject: Delivery Notification (DSN) - Failure MIME-Version: 1.0 Content-Type: multipart/report; report-type=delivery-status; boundary=JUK199912121934240002 --JUK199912121934240002 Content-type: text/plain Your message (id MM123456) to ifax@copper.point.com resulted in an error while attempting to decode the attached file. --JUK199912121934240002 Content-type: message/delivery-status Reporting-MTA: dns; copper.point.com Original-Envelope-ID: MM123456 Final-Recipient: rfc822;ifax@copper.point.com Action: Failed Status: 5.6.1 (Media not supported) Diagnostic-Code: smtp; 554 5.6.1 Decode error --JUK199912121934240002 Content-type: message/rfc822-headers Date: 1 June 1999 12:00:00 -0700 MIME-Version: 1.0 Content-Type: Image/Tiff Content-Transfer-Encoding: Base64 From: Jean To: IFax Message Holder Message-ID: <12345@water.line.com> --JUK199912121934240002-- Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 11] Internet draft Implementers Guide 31 October 2000 4.4.2.3 Failure Case Example 2 In this example the receiver determines it is unable to decode the attached TIFF file BEFORE it accepts the SMTP transmission. SMTP sequence: S: 220 copper.point.com SMTP service ready C: EHLO water.line.com S: 250-copper.point.com S: 250-DSN S: 250 ENHANCEDSTATUSCODES C: MAIL FROM: RET=HDRS ENVID=MM123456 S: 250 2.1.0 Originator ok C: RCPT TO: NOTIFY=SUCCESS,FAILURE ORCPT=rfc822; ifax@copper.point.com S: 250 2.1.5 Recipient ok C: DATA S: 354 Send message, ending in . S: Date: 1 June 1999 12:00:00 -0700 S: MIME-Version: 1.0 S: Content-Type: Image/Tiff S: Content-Transfer-Encoding: Base64 S: From: Jean S: To: IFax Message Holder S: Message-ID: <12345@water.line.com> S: S: JEKFEJFKEJKFEJKFJKEJFKEJEJKFEJFKJEKFEE S: EJFJEKFJEKFJEKJFEKJFKEJFKEFJEKFJKEJFKE S: . . . S: EJFKEJFKEJFKEJFKJEKFJEKJFKEJFKEKEFJKEJFE S: EJFKEJFKEJFKEJFKEKFJEKFJEKJFKEJFKEJFKEJF S: . S: 554 5.6.1 Media not supported C: QUIT S: 221 2.0.0 Goodbye DSN: Note: In this case, the previous MTA generates the DSN that is forwarded to the original sender. The receiving MTA has not accepted delivery and therefore can not generate a DSN. Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 12] Internet draft Implementers Guide 31 October 2000 4.4.3 Extended Mode Receivers that are POP3/IMAP4 NOTE: There are no new definitions here in this document. The definitions of disposition-types and disposition-modifiers are defined in RFC 2298[9]. This section provides examples on how POP3/IMAP4 devices may use the already defined values. These examples are provided as illustration only. They should not be interpreted as limiting the protocol or the MDN form. If the examples conflict with the definitions in the MDN [9] standard, the standard takes precedence. 4.4.3.1 Success Case Example If the original sender receives an MDNs which has "displayed", "dispatched" or "processed" disposition-type without disposition-modifier, the receiver may have possibly received or decoded the attached TIFF-FX file that it sent. It does not guarantee that the receiver displays, prints or saves the attached TIFF-FX file See Section 4.4.1.1, Discrepancies in MDN Interpretation. NOTE: This example does not include the third component of the MDN. Date: 14 Dec 1999 17:48:44 +0900 From: ken_recipient@bronze.dot.com Message-ID: <19991214174844.98765@silver.dot.com> Subject: Disposition Notification (MDN) - Success To: mary@silver.dot.com Mime-Version: 1.0 Content-Type: multipart/report; report-type=disposition-notification; boundary="61FD1001_IFAX" --61FD1001_IFAX Content-Type: text/plain This is a Return Receipt for the mail that you sent to "ken_recipient@bronze.dot.com". The message and attached files may have been printed, faxed or saved. This is no guarantee that the message has been read or understood. --61FD1001_IFAX Content-Type: message/disposition-notification Reporting-UA: ken-ifax.bronze.dot.com; barmail 1999.10 Original-Recipient: rfc822;ken_recipient@bronze.dot.com Final-Recipient: rfc822;ken_recipient@bronze.dot.com Original-Message-ID: <19991214174010O.mary@silver.dot.com> Disposition: automatic-action/MDN-send-automatically; dispatched --61FD1001_IFAX-- Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 13] Internet draft Implementers Guide 31 October 2000 4.4.3.2 Failure Case Example If the original sender receives an MDN with an "error" or "warning" disposition-modifier, it is possible that the receiver could not receive or decode the attached TIFF-FX file. Currently there is no mechanism to associate the disposition-type with the handling of the main content body of the message or the attached TIFF-FX file. Date: 14 Dec 1999 19:48:44 +0900 From: ken_recipient@bronze.dot.com Message-ID: <19991214194844.67325@silver.dot.com> Subject: Disposition Notification (MDN) - Failure To: mary@silver.dot.com Mime-Version: 1.0 Content-Type: multipart/report; report-type=disposition-notification; boundary="84FD1011_IFAX" --84FD1011_IFAX Content-Type: text/plain This is a Return Receipt for the mail that you sent to "ken_recipient@bronze.dot.com". A decoding error occurred in the attached file. --84FD1011_IFAX Content-Type: message/disposition-notification Reporting-UA: ken-ifax.bronze.dot.com; barmail 1999.10 Original-Recipient: rfc822;ken_recipient@bronze.dot.com Final-Recipient: rfc822;ken_recipient@bronze.dot.com Original-Message-ID: <199912141823123.mary@silver.dot.com> Disposition: automatic-action/MDN-send-automatically; processed/error --84FD1011_IFAX Content-Type: message/rfc822 [original message goes here] --84FD1011_IFAX-- Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 14] Internet draft Implementers Guide 31 October 2000 4.4.4 Receiving Multiple TIFF-FX Attachments A received email message could contain multiple TIFF-FX attachments and each distinct TIFF-FX file may use different encoding and/or resolution. A received email message could include TIFF-FX attachment and non-TIFF-FX attachments. There is currently no mechanism to identify, in a returned MDN, the attachments that were successfully decoded from those that could not be decoded. If the Extended Mode recipient is unable to decode any of the attached files, it is recommended that the Extended Mode recipient return a decoding error for the entire message. 5. Implementation Issues Specific to the File Format 5.1 IFD Placement in TIFF file & Profile S Constraints Low memory devices, which support resolutions greater than the required Profile-S, may be memory-constrained such that those devices cannot properly handle arbitrary placement of TIFF IFDs within a TIFF file. To interoperate with a receiver that is constrained, it is strongly recommended that senders always place the IFD at the beginning of the TIFF-FX file when using any of the Profiles defined in RFC 2301. 5.2 Precautions for implementers of RFC 2301 [4] The following compiled list of TIFF/RFC 2301 [4] errors were encountered during interoperability testing and is provided so that implementers of TIFF readers and writers can take precautionary measures. a) Although Profile S of TIFF-FX [4] specifies that files should be in little-endian order, during testing it was found that some common TIFF writers create big-endian files. If possible, the TIFF reader should be coded to handle big-endian files. TIFF writers should always create little-endian files to be compliant with the standard and to allow interoperation with memory-constrained devices; b) Bytes 0-1 of the Image File Header are supposed to be set to "II" (4949h) or "MM" (4d4dh) to indicate the byte order. During testing, other values were encountered. Readers should handle cases where the byte order field contain values other than "II" or "MM", and writers should ensure the correct value is used; Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 15] Internet draft Implementers Guide 31 October 2000 c) Bytes 2-3 of the Image File Header are the "magic number" and are supposed to be equal to 42 (2Ah). Readers should handle cases where the magic number is a different value, and writers should ensure the correct value is used; d) Readers should handle cases where IFD offsets point beyond the end of the TIFF-FX file, and writers should ensure the IFD offset does not point beyond the end of the file; e) Readers should be coded to handle the first IFD offset being on a non-word boundary, and writers should create the first IFD offset on a word boundary; f) Readers and writers should be careful to correctly handle IFDs with other TIFF profile data such as strip image data and header data. g) Some readers have difficulties with IFDs in certain locations. If possible, such reader implementations should be corrected and TIFF writers should take extra precautions to not place IFDs in these positions: IFD at the end of the profile, IFD intercalated with another IFD data like XResolution, DateTime, or strip image data. h) Some readers do not support child IFDs. Child IFDs should not be created by TIFF writers. i) Some readers do not recognize the GlobalParametersIFD. The GlobalParametersIFD should not be created by TIFF writers. 5.2.1 IFD Entry Errors Implementers should make sure when generating a TIFF profile that: a) All entries exist. Missing entries make it impossible to read the image data. b) Tags will not have two types of data (for example SHORT or LONG). c) Tags do not have the wrong type of data (for example RATIONAL instead of SRATIONAL). d) The count of type is correct for a specified tag (it is not null and the matches the tag ID) e) Tags appear in the right order in the IFD. Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 16] Internet draft Implementers Guide 31 October 2000 f) Tags as PageNumber or ImageLayer have values that match the number of IFDs or the image data. g) Tags are unique within an IFD. 5.2.2 Strip Errors Implementers should make sure when generating a TIFF profile that: a) Strip data is not overlapped with another file data b) The strip offset does not point outside file c) The strip length is not null or the strip offset + strip length does not point outside file d) There is only one bit order (not more) specified for data storing. 5.2.3 Image Errors a) Implementers should be cautious when generating a TIFF profile that the type of image tags and the data from the strip data match. For example, if in case of a black and white image the PhotometricInterpretation tag value is 0 (bit 0 means white) the image will appear inverted. b) Implementers should be cautious when generating a TIFF profile that for the special color spaces (ITULAB, YCBCR, CMYK) the parameters used for transformations are correct and compliant to the specification. c) Implementers should make sure when generating a TIFF profile that the tag values for XPosition and YPosition are correct. 5.2.4 Profile Specific Errors a) Implementers should make sure when generating a TIFF profile that all combinations of tag values are correct. Special attention should be given to the sets: XResolution, YResolution and ImageWidth and PhotometricInterpretation, SamplesPerPixel, and BitsPerSample. b) Implementers should make sure when generating a TIFF Profile M that the compression used for the layers is correct. Typical errors are for the Mask layer not be compressed with a black and white compression and the Background and Foreground layer not to be compressed with a color compression. Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 17] Internet draft Implementers Guide 31 October 2000 6. Implementation Issues for Internet Fax Addressing The "+" and "=" characters are valid within message headers, but are not valid values within some ESMTP commands, most notably ORCPT [5]. Implementations must take special care that ORCPT (and other ESMTP values) are properly encoded. For example, the following header is valid as-is: To: Home Fax but when used with ORCPT, the "=" and "+" must be encoded like this: RCPT TO: ORCPT=FAX+3D+2B290408565@faxmail.com Note the "=" and "+" are valid inside the forward-path, but must be encoded when used within the esmtp value. See [5] for details on this encoding. 7. Security considerations With regards to this document, Sections 5 in RFC 2305 [2] and Section 4 in RFC 2532 [3] apply. 8. Acknowledgements he authors gratefully acknowledge the following persons who contributed or made comments on earlier versions of this memo: Claudio Allocchio, Richard Coles, Ryuji Iwazaki, Graham Klyne, James Rafferty, and Kensuke Yamada. 9. References [1] RFC 2542, "Terminology and Goals for Internet Fax", Masinter, L., March 1999. [2] RFC 2305, "A Simple Mode of Facsimile Using Internet Mail", Toyoda, K., Ohno, H., Murai, J. and Wing, D., March 1998. [3] RFC 2532, "Extended Facsimile Using Internet Mail", Masinter, L. and Wing, D. March 1999. Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 18] Internet draft Implementers Guide 31 October 2000 [4] RFC 2301 "File Format for Internet Fax", McIntyre, L., Zilles, S., Buckley, R., Venable, D., Parsons, G. and J. Rafferty, March 1998. [5] RFC 1891 "SMTP Service Extension for Delivery Status Notification", Moore, K., January 1996. [6] RFC 1893 "Enhanced Mail System Status Codes", Vaudreuil, G., January 1996. [7] RFC 1894 "An Extensible Message Format for Delivery Status Notifications", Moore, K., Vaudreuil, G., January 1996. [8] RFC 2034 "SMTP Service Extension for Returning Enhanced Error Codes", Freed, N., October 1996. [9] RFC 2298 "An Extensible Message Format for Message Disposition Notifications", Fajman, R. March 1998. [10] RFC 822 "Standard for the Format of ARPA Internet Text Messages", Crocker. D., August 1982. [11] RFC 821 "A Simple Mail Transfer Protocol", Postel, D., August 1982. [12] RFC 2303 "Minimal PSTN address format in Internet Mail", Allocchio, C. March 1998 [13] RFC 2304 "Minimal FAX address format in Internet Mail", Allocchio, C. March 1998 [14] RFC 2846 "GSTN Address Element Extensions in E-mail Services", Allocchio, C. June 2000 [15] RFC 1869 "SMTP Service Extensions", Klensin, J., Freed, N., Rose, M., Stefferud, E., Crocker, D. November 1995 [16] RFC 2046 "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", Freed, N., Borenstein, N. November 1996 Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 19] Internet draft Implementers Guide 31 October 2000 10. Authors' addresses Vivian Cancio Xerox Corporation Mailstop PAHV-211 3400 Hillview Ave. Palo Alto, CA 94304 USA Telephone: +1-650-813-7591 Facsimile: +1-650-845-2341 Email: vivian.cancio@pahv.xerox.com Mike Moldovan G3 Nova Technology, Inc. 2794 Queens Way Thousand Oaks, CA 91362 USA Telephone: +1-805-245-4625 Facsimile: +1-805-245-4214 Email: mmoldovan@g3nova.com Hiroshi Tamura Ricoh Company, LTD. 2446 Toda, Atsugi City, Kanagawa-Pref., 243-0023 Japan Telephone: +81-46-228-1743 Facsimile: +81-46-228-7500 Email: tamura@toda.ricoh.co.jp Dan Wing Cisco Systems, Inc. 170 W. Tasman Drive San Jose, CA 95134-1706 USA Telephone: +1-408-525-5314 Facsimile: +1-408-527-8083 EMail: dwing@cisco.com Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 20] Internet draft Implementers Guide 31 October 2000 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. Cancio, Moldovan, Tamura, Wing Work-in-progress [Page 21] Internet draft Implementers Guide 31 October 2000 Revision history [[[RFC editor: Please remove this section on publication]]] Version 2 1) Changed first sentence of 4.4.1.1 2) Added Sections: 4.4.1.2, 4.4.1.3, 4.4.1.4, 4.4.2.1, 4.4.2.2, 4.4.2.3, 4.4.3.1, 4.4.3.2 and 4.4.4 3) Deleted Sections: 6 and 7 4) Changed heading of Section 4.4.1 5) In examples: replaced ifax@water.line.com with ifax@copper.point.com as well as other editorial changes in the examples through the document. 6) In examples: changed text in subject field of DSN 7) In examples: changed text in subject field of MDN 8) In examples: changed text in text field of MDN 9) Reworded text through out the document 10) Replaced heading in 5.2.1 [to "TIFF Readers: Be Cautious with Headers"] 11) " " 5.2.2 [to "TIFF Writers: Be Cautious in use of IFD"] Version 3 1) Section 5.2.1 and 5.2.2 were merged into 5.2; some of the Paragraphs in Section 5 were reworded for clarity. 2) The RFC 821 was added to the Reference section. 3) The Reference section format was modified for consistency. 4) A new Section 6 was added. 5) References [9], [10], [11], [12], [13], [14] & [15] were added in Section 6. 6) Description of [12], [13], [14] & [15] was added to the Reference section Version 4 Examples were improved and some of the text was improved or re-arranged. Section 6 was revised and simplified.