draft-iab-rfc-use-of-pdf-00.txt   draft-iab-rfc-use-of-pdf-01.txt 
Network Working Group T. Hansen, Ed. Network Working Group T. Hansen, Ed.
Internet-Draft AT&T Laboratories Internet-Draft AT&T Laboratories
Intended status: Informational L. Masinter Intended status: Informational L. Masinter
Expires: July 28, 2016 M. Hardy Expires: July 30, 2016 M. Hardy
Adobe Adobe
January 25, 2016 January 27, 2016
PDF for an RFC Series Output Document Format PDF for an RFC Series Output Document Format
draft-iab-rfc-use-of-pdf-00 draft-iab-rfc-use-of-pdf-01
Abstract Abstract
This document discusses options and requirements for the PDF This document discusses options and requirements for the PDF
rendering of RFCs in the RFC Series, as outlined in RFC 6949. It rendering of RFCs in the RFC Series, as outlined in RFC 6949. It
also discusses the use of PDF for Internet-Drafts, and available or also discusses the use of PDF for Internet-Drafts, and available or
needed software tools for producing and working with PDF. needed software tools for producing and working with PDF.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 28, 2016. This Internet-Draft will expire on July 30, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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4.2. Informative References . . . . . . . . . . . . . . . . . 14 4.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. History and Current Use of PDF with RFCs and Appendix A. History and Current Use of PDF with RFCs and
Internet-Drafts . . . . . . . . . . . . . . . . . . 15 Internet-Drafts . . . . . . . . . . . . . . . . . . 15
A.1. RFCs . . . . . . . . . . . . . . . . . . . . . . . . . . 15 A.1. RFCs . . . . . . . . . . . . . . . . . . . . . . . . . . 15
A.2. Internet-Drafts . . . . . . . . . . . . . . . . . . . . . 15 A.2. Internet-Drafts . . . . . . . . . . . . . . . . . . . . . 15
Appendix B. Paged Content Layout Quality . . . . . . . . . . . . 16 Appendix B. Paged Content Layout Quality . . . . . . . . . . . . 16
Appendix C. Tooling . . . . . . . . . . . . . . . . . . . . . . 16 Appendix C. Tooling . . . . . . . . . . . . . . . . . . . . . . 16
C.1. PDF Viewers . . . . . . . . . . . . . . . . . . . . . . . 17 C.1. PDF Viewers . . . . . . . . . . . . . . . . . . . . . . . 17
C.2. Printers . . . . . . . . . . . . . . . . . . . . . . . . 17 C.2. Printers . . . . . . . . . . . . . . . . . . . . . . . . 17
C.3. PDF Generation Libraries . . . . . . . . . . . . . . . . 17 C.3. PDF Generation Libraries . . . . . . . . . . . . . . . . 17
C.4. Typefaces . . . . . . . . . . . . . . . . . . . . . . . . 18 C.4. Typefaces . . . . . . . . . . . . . . . . . . . . . . . . 17
C.5. Other Tools . . . . . . . . . . . . . . . . . . . . . . . 18 C.5. Other Tools . . . . . . . . . . . . . . . . . . . . . . . 18
Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 19 Appendix D. Acknowledgements . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
The RFC Series is evolving, as outlined in [RFC6949]. Future The RFC Series is evolving, as outlined in [RFC6949]. Future
documents will use a canonical format, XML, with renderings in documents will use a canonical format, XML, with renderings in
various formats, including PDF. various formats, including PDF.
Because PDF has a wide range of capabilities and alternatives, not Because PDF has a wide range of capabilities and alternatives, not
all PDFs are "equal". For example, visually similar documents could all PDFs are "equal". For example, visually similar documents could
consist of scanned or rasterized images, or include text layout consist of scanned or rasterized images, or include text layout
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o The range of Unicode characters allowed in the XML source for o The range of Unicode characters allowed in the XML source for
Internet-Drafts and RFCs may be bounded by the availability of Internet-Drafts and RFCs may be bounded by the availability of
embeddable fonts with appropriate glyphs [I-D.flanagan-nonascii]. embeddable fonts with appropriate glyphs [I-D.flanagan-nonascii].
3.1.7. Hyphenation and Line Breaks 3.1.7. Hyphenation and Line Breaks
Typically, when doing page layout of running text, especially with Typically, when doing page layout of running text, especially with
narrow page width and long words, layout processors of English text narrow page width and long words, layout processors of English text
often have the option of hyphenating words, or using existing hyphens often have the option of hyphenating words, or using existing hyphens
as a place to introduce word breaks. However, line breaks inserted as a place to introduce word breaks. However, inserting line breaks
mid-word where the "word" is actually technically a sequence of mid-word can be harmful when the "word" is actually a sequence of
characters representing a protocol element or protocol sequence is characters representing a protocol element or protocol sequence.
actively harmful.
Recommendation: avoid introducing hyphenated line breaks mid-word Recommendation: avoid introducing hyphenated line breaks mid-word
into the visual display, consistent with requirements for plain text into the visual display, consistent with requirements for plain text
and HTML. and HTML.
3.1.8. Hyperlinks 3.1.8. Hyperlinks
PDF supports hyperlinks both to sections of the same document and to PDF supports hyperlinks both to sections of the same document and to
other documents. other documents.
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Appendix C. Tooling Appendix C. Tooling
This section discusses tools for viewing, comparing, creating, This section discusses tools for viewing, comparing, creating,
manipulating, transforming PDF files, including those currently in manipulating, transforming PDF files, including those currently in
use by the RFC editor and Internet-Drafts, as well as outlining use by the RFC editor and Internet-Drafts, as well as outlining
available PDF tools for various processes. available PDF tools for various processes.
C.1. PDF Viewers C.1. PDF Viewers
As with most file formats, PDF files are experienced through a reader As with most file formats, PDF files are experienced through a reader
or viewer of PDF files, and there are numerous viewers. One partial or viewer of PDF files. For most of the common platforms in use
list of PDF viewers can be found at <http://en.wikipedia.org/wiki/ (iOS, OS X, Windows, Android, ChromeOS, Kindle) and for most browsers
List_of_PDF_software#Viewers>. (Edge, Safari, Chrome, Firefox), PDF viewing is built in. In
addition there are many PDF viewers available for download and
install.
PDF viewers vary in capabilities, and it is important to note which PDF viewers vary in capabilities, and it is important to note which
PDF viewers support the features utilized in PDF RFCs and Internet- PDF viewers support the features utilized in PDF RFCs and Internet-
Drafts (features such as links, digital signatures, Tagged PDF and Drafts (features such as links, digital signatures, Tagged PDF and
others mentioned in Section 3). others mentioned in Section 3).
A survey of the IETF community might broaden the list of viewers in
common use, but an initial list to consider include some that are
currently maintained and supported viewers and legacy systems.
Maintained viewers include:
Adobe Reader Multiple platforms. Supports all of the features on
most platforms.
Google Chrome Multiple platforms. Web browser which includes PDF
support. Rapidly moving target, open source.
PDF.js Multiple platforms. A JavaScript library to convert PDF
files into HTML5, usable as a web-based viewer that can be
included in web browsers. Used by Mozilla Firefox. Also rapidly
moving target.
Foxit Reader Multiple platforms. PDF Viewer / Reader for Desktop
computer and Mobile Devices. Recently licensed by Google, and the
code for this purpose was made open source; see <http://www.i-
programmer.info/news/136-open-source/7433-google-open-sources-pdf-
software-library.html>.
Several "legacy" viewers to consider include: Ghostview, Xpdf.
C.2. Printers C.2. Printers
While almost all viewers also support printing of PDF files, printing While almost all viewers also support printing of PDF files, printing
is one of the most important use cases for PDFs. Some printers have is one of the most important use cases for PDFs. Some printers have
direct PDF support. direct PDF support.
C.3. PDF Generation Libraries C.3. PDF Generation Libraries
Because the xml2rfc format is a unique format, software for Because the xml2rfc format is a unique format, software for
converting XML source documents to the various formats will be converting XML source documents to the various formats will be
needed, including PDF generation. needed, including PDF generation.
One promising direction is suggested in One promising direction is suggested in
<http://greenbytes.de/tech/webdav/rfc2629xslt/ <http://greenbytes.de/tech/webdav/rfc2629xslt/
rfc2629xslt.html#output.pdf.fop>: using XSLT to generate XSL-FO which rfc2629xslt.html#output.pdf.fop>: using XSLT to generate XSL-FO which
is then processed by a formatting object processor such as Apache is then processed by a formatting object processor such as Apache
FOP. FOP.
Several libraries are also available for generating PDF signatures. Several libraries are also available for generating PDF signatures.
The choice of library to use for xml2pdf will depend on many factors:
programming language, quality of implementation, quality of PDF
generated, support, cost, availability, and so forth.
C.4. Typefaces C.4. Typefaces
This section is intended to discuss available typefaces that might This section is intended to discuss available typefaces that might
satisfy requirements. Some openly available fixed-width typefaces satisfy requirements. Some openly available fixed-width typefaces
(without extensive Unicode support, however) include: (without extensive Unicode support, however) include:
o Source Sans [1] o Source Sans [1]
o Source Serif Pro [2] o Source Serif Pro [2]
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