| Network Working Group | M. Hardy |
| Internet-Draft | L. Masinter |
| Obsoletes: 3778 (if approved) | D. Markovic |
| Intended status: Informational | Adobe |
| Expires: October 9, 2016 | D. Johnson |
| PDF Association | |
| M. Bailey | |
| Global Graphics | |
| April 7, 2016 |
The application/pdf Media Type
draft-hardy-pdf-mime-01
The Portable Document Format (PDF) is an ISO standard (ISO 32000-1:2008) defining a final-form document representation language in use for document exchange, including on the Internet, since 1993. This document provides an overview of the PDF format and updates the media type registration of application/pdf.
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This document is intended to provide updated information on the registration of the MIME Media Type application/pdf for documents defined in the PDF [ISOPDF], "Portable Document Format", syntax.
PDF was originally envisioned as a way to reliably communicate and view printed information electronically across a wide variety of machine configurations, operating systems, and communication networks.
PDF is used to represent "final form" formatted documents. PDF pages may include text, images, graphics and multimedia content such as video and audio. PDF is also capable of containing auxiliary structures including annotations, bookmarks, file attachments, hyperlinks, logical structure and metadata. These features are useful for navigation, building collections of related documents and for reviewing and commenting on documents. A rich JavaScript model has been defined for interacting with PDF documents.
PDF used the imaging model of the PostScript [PS] page description language to render complex text, images, and graphics in a device and resolution-independent manner.
PDF supports encryption and digital signatures. The encryption capability is combined with access control information to facilitate management of the functionality available to the recipient. PDF supports the inclusion of document and object-level metadata through the eXtensible Metadata Platform[XMP].
PDF is used widely in the Internet community. The first version of PDF, 1.0, was published in 1993 by Adobe Systems. Since then PDF has grown to be a widely-used format for capturing and exchanging formatted documents electronically across the Web, via e-mail and virtually every other document exchange mechanism. In 2008, PDF 1.7 was published as an ISO standard [ISOPDF], ISO 32000-1:2008.
The ISO TC-171 committee is presently working on a refresh of PDF, known as ISO 32000-2, with a version of PDF 2.0, expected to be published in 2017.
In addition to ISO 32000-1:2008 and 32000-2, several subset standards have been defined to address specific use cases and standardized by the ISO. These standards include PDF for Archival (PDF/A), PDF for Engineering (PDF/E), PDF for Universal Accessibility (PDF/UA), PDF for Variable Data and Transactional Printing (PDF/VT) and PDF for Prepress Digital Data Exchange (PDF/X). The subset standards are fully compliant PDF files capable of being displayed in a general PDF viewer.
A set of fragment identifiers [RFC3986] and their handling are defined in ISO 32000-2 [ISOPDF2]. This section summarizes that material.
A fragment identifier is comprised of one or more parameters separated by the AMPERSAND (&) character. Each parameter implies an action to be performed on the document and provides values to be used for that action; the values for a parameter are introduced by an EQUAL SIGN (=) and separated by a COMMA (,); values which are strings appear in the fragment identifier using URI's percent-hex escaping -- spaces, reserved and non-ASCII strings are included by %nn encoding the UTF-8 of each character. Actions shall be processed and executed from left to right as they appear in the character string that makes up the fragment identifier.
The parameters listed in this section operate on the document at the point it is opened; for this reason they are sometimes referred to as PDF open parameters. The fragment identifier should be processed immediately after document-specified open parameters have been processed.
The table below lists the PDF open parameters relevant to PDF. All coordinate values (left, right, top, and bottom) shall be expressed in the default user space coordinate system.
PDF Open Parameters
| Parameter Name | Arguments | Description |
|---|---|---|
| nameddest | name | Open the document to the specified named destination. The argument provided is a string which shall correspond to the name of a destination in the target document. |
| page | pageNum | Open the document to the specified page number. The argument shall be a positive integer number. The first page in the document has a pageNum value of 1. |
| zoom | scale scale,left,top | Open the document with the specified zoom level and optional offset. The scale argument shall be either an integer or floating point value representing the percentage to which the document should be zoomed, where a value of 100 would correspond to a zoom of 100%. The left and top arguments are optional, but shall both be specified if either is included. The left and top arguments shall be integer or floating point values representing the offset from the left and top of the page in a coordinate system where 0,0 represents the top left corner of the page. |
| view | keyword,position | Open the document with the specified destination set as the view. The arguments shall correspond to those found in [ISOPDF2] 12.3.2.2, "Explicit destinations". The keyword shall correspond to one of the keywords defined in [ISOPDF2] Table 149, "Destination syntax" with appropriate position values. |
| viewrect | left,top,width,height | Open the document with the specified window view rectangle. The left and top arguments shall be integer or floating point values representing the offset from the left and top of the page in a coordinate system where 0,0 represents the top left corner of the page. The width and height arguments shall be integer or floating point values representing the width and height of the view. |
| highlight | left,right,top,bottom | Open the document with the specified rectangle highlighted. Each argument shall be an integer or floating point value representing the rectangle measured from the top left corner of the page. |
| comment | commentID | Open the document with the specified comment selected. The commentID shall be the value of an annotation name, which is defined by the NM key in the corresponding annotation dictionary (see 12.5.2 "Annotation dictionaries", Table 167). If the comment parameter is combined with another parameter that defines a specific page to be displayed, then the comment parameter shall appear after that in the URI. Note: The NM key is unique to a specific page, but is not guaranteed to be unique to a document. Unless the page on which the comment resides has been selected prior to the comment parameter, the comment will not be selected. |
| search | wordList | Open the document and search for one or more words, selecting the first matching word in the document. The wordList argument defines the search words and shall be a string enclosed within quotation marks comprised of individual words separated by space characters. Note that the space characters must be encoded. |
| fdf | URI | Open the document and then import the data from the specified FDF or XFDF file. The URI shall be either a relative or absolute URI to an FDF or XFDF file. The fdf parameter should be specified as the last parameter to a given URI. Note: The fdf parameter is recommended to be the last parameter so that the document can open directly to the appropriate view. |
Several subsets of PDF have been published as distinct ISO standards:
All of these subset standards use application/pdf media type. The subset standards are generally not exclusive, so it is possible to construct a PDF file which conforms to, for example, both PDF/A-2b and PDF/X-4 subset standards.
PDF documents claiming conformance to one or more of the subset standards use XMP metadata to identify levels of conformance. PDF processors should examine document metadata streams for such subset standards identifiers and, if apropriate, label documents as such when presenting them to the user.
PDF format has gone through several revisions, primarily for the addition of features. PDF features have generally been added in a way that older viewers 'fail gracefully' because they can just ignore features they do not recognize, but even so, the older the PDF version produced, the more legacy viewers will support that version, but the fewer features will be enabled.
PDF files are experienced through a reader or viewer of PDF files. For most of the common platforms in use (iOS, OS X, Windows, Android, ChromeOS, Kindle) and for most browsers (Edge, Safari, Chrome, Firefox), PDF viewing is built-in. In addition, there are many PDF viewers available for download and install. The PDF specification was published and freely available since the format was introduced in 1993, so hundreds of companies and organizations make tools for PDF creation, viewing, and manipulation.
The PDF file format allows several constructs which may compromise security if handled inadequately by PDF processors. For example:
In addition, the PDF processor itself, as well as its plugins, scripts etc. may be a source of insecurity, by either obvious or subtle means.
This document updates the registration of application/pdf, a media type registration as defined in [RFC6838]:
Type name: application
Subtype name: pdf
Required parameters: none
Optional parameter: none
Encoding considerations: binary
Security considerations: See Section 6 of this document.
Interoperability considerations: See Section 5 of this document.
Published specification: ISO 32000-1:2008 (PDF 1.7) [ISOPDF]. ISO 32000-2 (PDF 2.0) [ISOPDF2] is currently under development.
Applications which use this media type: See Section 5 of this document.
Fragment identifier considerations: See Section 3 of this document.
Additional information:
Deprecated alias names for this type: none
Magic number(s): All PDF files start with the characters '%PDF-' followed by the PDF version number, e.g., "%PDF-1.7". These characters are in US-ASCII encoding.
File extension(s): .pdf
Macintosh file type code(s): "PDF "
Person & email address to contact for further information: Duff Johnson <duff@duff-johnson.com>, Peter Wyatt <Peter.wyatt@cisra.canon.com.au>, ISO 32000 Project Leaders
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: ISO 32000 is by ISO/TC 171/SC 02/WG 08, "PDF specification". Duff Johnson <duff@duff-johnson.com> and Peter Wyatt <Peter.wyatt@cisra.canon.com.au are current ISO 32000 Project Leaders.
This specification replaces RFC 3778, which previously defined the application/pdf Media Type. Differences include:
To reflect the transition from a proprietary specification by Adobe to an open ISO Standard, the Change Controller has changed from Adobe to ISO, and references updated.
The overview of PDF capabilitiies, the history of PDF, and the descriptions of PDF subsets were updated to reflect more recent relevant history.
The section on Fragment identifiers was updated to closely reflect the material which has been added to ISO-32000-2.
The status of popular PDF impelementations was updatd.
The Security Considerations were updated to match current status.
The registration template was updated to match RFC 6838.