可移植文档格式：修订间差异

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|quote=This document describes the base technology and ideas behind the project named “Camelot.” This project’s goal is to solve a fundamental problem [...] there is no universal way to communicate and view ... printed information electronically.}}</ref>演變成PDF。
|quote=This document describes the base technology and ideas behind the project named “Camelot.” This project’s goal is to solve a fundamental problem [...] there is no universal way to communicate and view ... printed information electronically.}}</ref>演變成PDF。


在Adobe Systems决定PDF规范在1993年可以自由使用的时候，PDF是由Adobe控制的{{link-en|专有格式|proprietary format}}，直到2008年7月1日官方作为{{link-en|开放标准|open standard}}发行，并由[[国际标准化组织]]以ISO 32000-1:2008标准发布，<ref name="iso-standard">{{cite web|url=http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=51502 |title=ISO 32000-1:2008 - Document management – Portable document format – Part 1: PDF 1.7 |publisher=Iso.org |date=2008-07-01 |accessdate=2010-02-21}}</ref><ref>{{cite web | last = Orion | first = Egan | title = PDF 1.7 is approved as ISO 32000 | work = [[The Inquirer]] | publisher = [[The Inquirer]] | date = 2007-12-05 | url = http://www.theinquirer.net/gb/inquirer/news/2007/12/05/pdf-approved-iso-32000 | accessdate = 2007-12-05 }}; {{cite web | url = http://www.vnunet.com/vnunet/news/2205065/pdf-takes-first-step-towards | title = Adobe wins backing for PDF 1.7 | publisher = vnunet.com }}</ref>在这段时间规范通过ISO志愿者产业专家委员会控制。2008年，Adobe发布对ISO 32000-1的公共专利许可赋予对所有Adobe拥有的制作、使用、销售及分发兼容PDF的实现所需的专利的自由授权（[[:en:Royalty-free|Royalty-free]]）的权益。<ref>{{citation |url=https://www.adobe.com/pdf/pdfs/ISO32000-1PublicPatentLicense.pdf |title=Public Patent License, ISO 32000-1: 2008 – PDF 1.7 |author=Adobe Systems Incorporated |year=2008 |accessdate=2011-07-06}}</ref>然而仍有一些ISO 32000-1所引用的可以被纳入有效的PDF文件的技术保持专有（但仍是公开记录），如[[XFA|Adobe XML表单架构]]，以及JavaScript for Acrobat。<ref>{{cite web |url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=SWD:2013:0224:FIN:EN:PDF |title=Guide for the procurement of standards-based ICT - Elements of Good Practice, Against lock-in: building open ICT systems by making better use of standards in public procurement |quote=Example: ISO/IEC 29500, ISO/IEC 26300 and ISO 32000 for document formats reference information that is not accessible by all parties (references to proprietary technology and brand names, incomplete scope or dead web links). |publisher=European Commission |date=2013-06-25 |accessdate=2013-10-20}}</ref><ref name="iso-meeting-n603" /><ref>{{cite web |url=http://www.plosone.org/article/fetchSingleRepresentation.action?uri=info:doi/10.1371/journal.pone.0069446.s001 |title=Embedding and publishing interactive, 3-dimensional, scientificfigures in Portable Document Format (PDF) files |quote=... the implementation of the U3D standard was not complete and proprietary extensions were used. |accessdate=2013-10-20}}</ref><ref name="rosenthol-adobe-2012" /><ref>{{citation |url=http://www.planetpdf.com/enterprise/article.asp?ContentID=Is_PDF_an_open_standard&page=1 |title=Is PDF an open standard? - Adobe Reader is the de facto Standard, not PDF |author=Duff Johnson |date=2010-06-10 |accessdate=2014-01-19}}</ref>ISO委员会正活跃地制定许多这类的标准作为ISO 32000-2的一部分。
在Adobe Systems决定PDF规范在1993年可以自由使用的时候，PDF是由Adobe控制的{{link-en|专有格式|proprietary format}}，直到2008年7月1日官方作为{{link-en|开放标准|open standard}}发行，并由[[国际标准化组织]]以ISO 32000-1:2008标准发布，<ref name="iso-standard">{{cite web|url=http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=51502 |title=ISO 32000-1:2008 - Document management – Portable document format – Part 1: PDF 1.7 |publisher=Iso.org |date=2008-07-01 |accessdate=2010-02-21}}</ref><ref>{{cite web | last = Orion | first = Egan | title = PDF 1.7 is approved as ISO 32000 | work = [[The Inquirer]] | publisher = [[The Inquirer]] | date = 2007-12-05 | url = http://www.theinquirer.net/gb/inquirer/news/2007/12/05/pdf-approved-iso-32000 | accessdate = 2007-12-05 }}; {{cite web | url = http://www.vnunet.com/vnunet/news/2205065/pdf-takes-first-step-towards | title = Adobe wins backing for PDF 1.7 | publisher = vnunet.com }}</ref>在这段时间规范通过ISO志愿者产业专家委员会控制。2008年，Adobe发布对ISO 32000-1的公共专利许可赋予对所有Adobe拥有的制作、使用、销售及分发兼容PDF的实现所需的专利的自由授权的权益。<ref>{{citation |url=https://www.adobe.com/pdf/pdfs/ISO32000-1PublicPatentLicense.pdf |title=Public Patent License, ISO 32000-1: 2008 – PDF 1.7 |author=Adobe Systems Incorporated |year=2008 |accessdate=2011-07-06}}</ref>然而仍有一些ISO 32000-1所引用的可以被纳入有效的PDF文件的技术保持专有（但仍是公开记录），如[[XFA|Adobe XML表单架构]]，以及JavaScript for Acrobat。<ref>{{cite web |url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=SWD:2013:0224:FIN:EN:PDF |title=Guide for the procurement of standards-based ICT - Elements of Good Practice, Against lock-in: building open ICT systems by making better use of standards in public procurement |quote=Example: ISO/IEC 29500, ISO/IEC 26300 and ISO 32000 for document formats reference information that is not accessible by all parties (references to proprietary technology and brand names, incomplete scope or dead web links). |publisher=European Commission |date=2013-06-25 |accessdate=2013-10-20}}</ref><ref name="iso-meeting-n603" /><ref>{{cite web |url=http://www.plosone.org/article/fetchSingleRepresentation.action?uri=info:doi/10.1371/journal.pone.0069446.s001 |title=Embedding and publishing interactive, 3-dimensional, scientificfigures in Portable Document Format (PDF) files |quote=... the implementation of the U3D standard was not complete and proprietary extensions were used. |accessdate=2013-10-20}}</ref><ref name="rosenthol-adobe-2012" /><ref>{{citation |url=http://www.planetpdf.com/enterprise/article.asp?ContentID=Is_PDF_an_open_standard&page=1 |title=Is PDF an open standard? - Adobe Reader is the de facto Standard, not PDF |author=Duff Johnson |date=2010-06-10 |accessdate=2014-01-19}}</ref>ISO委员会正活跃地制定许多这类的标准作为ISO 32000-2的一部分。


== 歷史 ==
== 歷史 ==
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=== GB标准化 ===
=== GB标准化 ===
2009年9月1日，作为电子文档长期保存格式的PDF/Archive（PDF/A）经[[中国国家标准化管理委员会]]批准已成为正式的[[中华人民共和国国家标准]]（GB）<ref>{{Cite news|url=http://tech.sina.com.cn/s/2009-07-13/1809982373.shtml|title=9月1日起PDF格式成为中国国家标准|publisher=新浪科技|date=2009-07-03|language=zh-cn}}</ref>，标准号为GB/T 23286.1-2009<ref>{{cite web|url=http://www.sac.gov.cn/SACSearch/search?channelid=160591&templet=gjcxjg_detail.jsp&searchword=STANDARD_CODE='GB/T%2023286.1-2009'&XZ=T|title=文献管理长期保存的电子文档文件格式第1部分：PDF1.4（PDF/A-1）的使用|publisher=国家标准化管理委员会|language=zh-cn}}</ref>。
2009年9月1日，作为电子文档长期保存格式的PDF/Archive（PDF/A）经[[中国国家标准化管理委员会]]批准已成为正式的[[中华人民共和国国家标准]]（GB）<ref>{{Cite news|url=http://tech.sina.com.cn/s/2009-07-13/1809982373.shtml|title=9月1日起PDF格式成为中国国家标准|publisher=新浪科技|date=2009-07-03|language=zh-cn}}</ref>，标准号为GB/T 23286.1-2009<ref>{{cite web|url=http://www.sac.gov.cn/SACSearch/search?channelid=160591&templet=gjcxjg_detail.jsp&searchword=STANDARD_CODE='GB/T%2023286.1-2009'&XZ=T|title=文献管理长期保存的电子文档文件格式第1部分：PDF1.4（PDF/A-1）的使用|publisher=国家标准化管理委员会|language=zh-cn}}</ref>。
== 技術 ==
== 技术基础 ==
任何人可以创建能阅读和编写PDF而不需要给[[Adobe Systems]]支付版税的应用；Adobe对PDF持有专利，但以自由授权（[[:en:Royalty-free|Royalty-free]]）的方式许可使用于开发遵从PDF规格的应用。<ref>[http://partners.adobe.com/public/developer/support/topic_legal_notices.html partners.adobe.com - Developer Resources]</ref>

PDF主要由三項技術組成：
PDF主要由三項技術組成：
* 衍生自[[PostScript]]，可以說是[[PostScript]]的缩略版。
* 衍生自[[PostScript]]的頁面描述語言子集，用以生成和輸出圖形。
* [[字型]]嵌入系統，可使字型隨文件一起傳輸。
* [[字型]]嵌入/替換系統，可使字型隨文件一起傳輸。
* 結構化的存儲系統，用以綁定這些元素和任何相關内容到單個檔案，帶有適當的資料[[壓縮]]系統。
* 資料[[壓縮]]及传輸系統。
{{transH}}
=== PostScript ===
[[PostScript]] is a [[page description language]] run in an [[interpreter (computing)|interpreter]] to generate an image, a process requiring many resources. It can handle not just graphics, but standard features of [[programming language]]s such as <code>if</code> and <code>loop</code> commands. PDF is largely based on PostScript but simplified to remove flow control features like these, while graphics commands such as <code>lineto</code> remain.

Often, the PostScript-like PDF code is generated from a source PostScript file. The graphics commands that are output by the PostScript code are collected and [[Lexical analysis|tokenized]]; any files, graphics, or fonts to which the document refers also are collected; then, everything is compressed to a single file. Therefore, the entire PostScript world (fonts, layout, measurements) remains intact.

As a document format, PDF has several advantages over PostScript:
* PDF contains tokenized and interpreted results of the PostScript source code, for direct correspondence between changes to items in the PDF page description and changes to the resulting page appearance.
* PDF (from version 1.4) supports true [[transparency (graphic)|graphic transparency]]; PostScript does not.
* PostScript is an [[interpreted programming language]] with an implicit global state, so instructions accompanying the description of one page can affect the appearance of any following page. Therefore, all preceding pages in a PostScript document must be processed to determine the correct appearance of a given page, whereas each page in a PDF document is unaffected by the others. As a result, PDF viewers allow the user to quickly jump to the final pages of a long document, whereas a PostScript viewer needs to process all pages sequentially before being able to display the destination page (unless the optional PostScript [[Document Structuring Conventions]] have been carefully complied with).

== 技术概括 ==

=== 文件结构 ===
A PDF file is a subset of a COS ("Carousel" Object Structure) format. COS is also with FDF files.<ref>http://jimpravetz.com/blog/2012/12/in-defense-of-cos/</ref> A COS tree file consists primarily of ''objects'', of which there are eight types:<ref>Adobe Systems, PDF Reference, p. 51.</ref>
* [[Boolean data type|Boolean]] values, representing ''true'' or ''false''
* Numbers
* [[String (computer science)|Strings]]
* Names
* [[Array data type|Array]]s, ordered collections of objects
* [[Dictionary (data structure)|Dictionaries]], collections of objects indexed by Names
* [[Stream (computing)|Streams]], usually containing large amounts of data
* The [[Pointer (computer programming)|null]] object

Objects may be either ''direct'' (embedded in another object) or ''indirect''. Indirect objects are numbered with an ''object number'' and a ''generation number''. An index table called the ''xref table'' gives the byte offset of each indirect object from the start of the file.<ref>Adobe Systems, PDF Reference, pp. 39–40.</ref> This design allows for efficient [[random access]] to the objects in the file, and also allows for small changes to be made without rewriting the entire file (''incremental update''). Beginning with PDF version 1.5, indirect objects may also be located in special streams known as ''object streams''. This technique reduces the size of files that have large numbers of small indirect objects and is especially useful for ''Tagged PDF''.

There are two layouts to the PDF files: non-linear (not "optimized") and linear ("optimized"). Non-linear PDF files consume less disk space than their linear counterparts, though they are slower to access because portions of the data required to assemble pages of the document are scattered throughout the PDF file. Linear PDF files (also called "optimized" or "web optimized" PDF files) are constructed in a manner that enables them to be read in a Web browser plugin without waiting for the entire file to download, since they are written to disk in a linear (as in page order) fashion.<ref name="pdf-ref"/> PDF files may be optimized using [[Adobe Acrobat]] software or [[QPDF]].

=== 图像模式 ===
The basic design of how [[graphics]] are represented in PDF is very similar to that of PostScript, except for the use of [[transparency (graphic)|transparency]], which was added in PDF 1.4.

PDF graphics use a [[device independent]] [[Cartesian coordinate system]] to describe the surface of a page. A PDF page description can use a [[matrix (mathematics)|matrix]] to [[scale (ratio)|scale]], [[rotate]], or [[Shear mapping|skew]] graphical elements. A key concept in PDF is that of the ''graphics state'', which is a collection of graphical parameters that may be changed, saved, and restored by a ''page description''. PDF has (as of version 1.6) 24 graphics state properties, of which some of the most important are:
* The ''current transformation matrix'' (CTM), which determines the coordinate system
* The ''[[clipping path]]''
* The ''[[color space]]''
* The ''[[alpha compositing|alpha constant]]'', which is a key component of transparency

==== 矢量图 ====
[[Vector graphics]] in PDF, as in PostScript, are constructed with ''paths''. Paths are usually composed of lines and cubic [[Bézier curve]]s, but can also be constructed from the outlines of text. Unlike PostScript, PDF does not allow a single path to mix text outlines with lines and curves. Paths can be stroked, filled, or used for [[clipping path|clipping]]. Strokes and fills can use any color set in the graphics state, including ''patterns''.

PDF supports several types of patterns. The simplest is the ''tiling pattern'' in which a piece of artwork is specified to be drawn repeatedly. This may be a ''colored tiling pattern'', with the colors specified in the pattern object, or an ''uncolored tiling pattern'', which defers color specification to the time the pattern is drawn. Beginning with PDF 1.3 there is also a ''shading pattern'', which draws continuously varying colors. There are seven types of shading pattern of which the simplest are the ''axial shade'' (Type 2) and ''radial shade'' (Type 3). <!-- Pictures desperately needed here! -->

==== 位图 ====
[[Raster graphics|Raster images]] in PDF (called ''Image XObjects'') are represented by dictionaries with an associated stream. The dictionary describes properties of the image, and the stream contains the image data. (Less commonly, a raster image may be embedded directly in a page description as an ''inline image''.) Images are typically ''filtered'' for compression purposes. Image filters supported in PDF include the general purpose filters
* '''ASCII85Decode''' a filter used to put the stream into 7-bit [[ASCII]]
* '''ASCIIHexDecode''' similar to ASCII85Decode but less compact
* '''FlateDecode''' a commonly used filter based on the [[zlib]]/[[deflate]] algorithm (a.k.a. [[gzip]], but not [[ZIP (file format)|zip]]) defined in RFC 1950 and RFC 1951; introduced in PDF 1.2; it can use one of two groups of predictor functions for more compact zlib/deflate compression: ''Predictor 2'' from the [[TIFF]] 6.0 specification and predictors (filters) from the [[Portable Network Graphics|PNG]] specification (RFC 2083)
* '''LZWDecode''' a filter based on [[LZW]] Compression; it can use one of two groups of predictor functions for more compact LZW compression: ''Predictor 2'' from the TIFF 6.0 specification and predictors (filters) from the PNG specification
* '''RunLengthDecode''' a simple compression method for streams with repetitive data using the [[run-length encoding]] algorithm and the image-specific filters
* '''DCTDecode''' a [[lossy]] filter based on the [[JPEG]] standard
* '''CCITTFaxDecode''' a [[lossless]] [[bi-level image|bi-level]] (black/white) filter based on the Group 3 or [[Group 4 compression|Group 4]] [[CCITT]] (ITU-T) [[fax]] compression standard defined in ITU-T [[T.4]] and T.6
* '''JBIG2Decode''' a lossy or lossless bi-level (black/white) filter based on the [[JBIG2]] standard, introduced in PDF 1.4
* '''JPXDecode''' a lossy or lossless filter based on the [[JPEG 2000]] standard, introduced in PDF 1.5

Normally all image content in a PDF is embedded in the file. But PDF allows image data to be stored in external files by the use of ''external streams'' or ''Alternate Images''. Standardized subsets of PDF, including [[PDF/A]] and [[PDF/X]], prohibit these features.

==== 文本 ====
Text in PDF is represented by ''text elements'' in page content streams. A text element specifies that ''characters'' should be drawn at certain positions. The characters are specified using the ''encoding'' of a selected ''font resource''.

===== 字体 =====
A font object in PDF is a description of a digital [[typeface]]. It may either describe the characteristics of a typeface, or it may include an embedded ''font file''. The latter case is called an ''embedded font'' while the former is called an ''unembedded font''. The font files that may be embedded are based on widely used standard digital font formats: '''[[PostScript fonts|Type 1]]''' (and its compressed variant '''CFF'''), '''[[TrueType]]''', and (beginning with PDF 1.6) '''[[OpenType]]'''. Additionally PDF supports the '''Type 3''' variant in which the components of the font are described by PDF graphic operators. <!--- Type 3 bit is awkward and should be cleaned up --->

===== Standard Type 1字体（Standard 14字体） =====
Fourteen typefaces, known as the ''standard 14 fonts'', have a special significance in PDF documents:
* [[Times Roman|Times]] (v3) (in regular, italic, bold, and bold italic)
* [[Courier (typeface)|Courier]] (in regular, oblique, bold and bold oblique)
* [[Helvetica]] (v3) (in regular, oblique, bold and bold oblique)
* [[Symbol (typeface)|Symbol]]
* [[Zapf Dingbats]]
These fonts are sometimes called the ''base fourteen fonts''.<ref>[http://desktoppub.about.com/od/glossary/g/base14fonts.htm Adobe Acrobat Base 14 Fonts]</ref> These fonts, or suitable substitute fonts with the same metrics, must always be available in all PDF readers and so need not be embedded in a PDF.<ref>[http://www.planetpdf.com/planetpdf/pdfs/pdf2k/03e/merz_fontaquarium.pdf The PDF Font Aquarium]</ref> PDF viewers must know about the metrics of these fonts. Other fonts may be substituted if they are not embedded in a PDF.

===== 编码 =====
Within text strings, characters are shown using ''character codes'' (integers) that map to glyphs in the current font using an ''encoding''. There are a number of predefined encodings, including ''WinAnsi'', ''MacRoman'', and a large number of encodings for East Asian languages, and a font can have its own built-in encoding. (Although the WinAnsi and MacRoman encodings are derived from the historical properties of the [[Microsoft Windows|Windows]] and [[Macintosh]] operating systems, fonts using these encodings work equally well on any platform.) PDF can specify a predefined encoding to use, the font's built-in encoding or provide a lookup table of differences to a predefined or built-in encoding (not recommended with TrueType fonts).<ref>{{cite web|url=https://www.adobe.com/devnet/acrobat/pdfs/pdf_reference_1-7.pdf |title=PDF Referencem Sixth Edition, version 1.7, table 5.11}}</ref> The encoding mechanisms in PDF were designed for Type 1 fonts, and the rules for applying them to TrueType fonts are complex.

For large fonts or fonts with non-standard glyphs, the special encodings ''Identity-H'' (for horizontal writing) and ''Identity-V'' (for vertical) are used. With such fonts it is necessary to provide a ''ToUnicode'' table if semantic information about the characters is to be preserved.

==== 透明度 ====
The original imaging model of PDF was, like PostScript's, ''opaque'': each object drawn on the page completely replaced anything previously marked in the same location. In PDF 1.4 the imaging model was extended to allow transparency. When transparency is used, new objects interact with previously marked objects to produce blending effects. The addition of transparency to PDF was done by means of new extensions that were designed to be ignored in products written to the PDF 1.3 and earlier specifications. As a result, files that use a small amount of transparency might view acceptably in older viewers, but files making extensive use of transparency could be viewed incorrectly in an older viewer without warning.

The transparency extensions are based on the key concepts of ''transparency groups'', ''blending modes'', ''shape'', and ''alpha''. The model is closely aligned with the features of [[Adobe Illustrator]] version 9. The blend modes were based on those used by [[Adobe Photoshop]] at the time. When the PDF 1.4 specification was published, the formulas for calculating blend modes were kept secret by Adobe. They have since been published.<ref>[https://www.adobe.com/content/dam/Adobe/en/devnet/pdf/pdfs/pdf_reference_archives/blend_modes.pdf PDF Blend Modes Addendum]</ref>

The concept of a transparency group in PDF specification is independent of existing notions of "group" or "layer" in applications such as Adobe Illustrator. Those groupings reflect logical relationships among objects that are meaningful when editing those objects,
but they are not part of the imaging model.

=== 交互元素 ===

PDF files may contain interactive elements such as annotations, form fields, video and Flash animation.

'''Rich Media PDF''' is a term that is used to describe interactive content that can be embedded or linked to inside of a PDF. This content must be produced using the Flash file format. When Adobe bought Macromedia, the jewel of the company was Flash, and the Flash player was embedded inside Adobe Acrobat and Adobe Reader, removing the need for third-party plug-ins such as Flash, QuickTime, or Windows Media. Unfortunately, this caused a rift with Apple as QuickTime video was prohibited from PDF. Rich Media expert [[Bob Connolly (Canadian film director)#Books.2C eBooks and Magazine Articles|Robert Connolly]], believes this event triggered the war between Apple and Adobe over the Flash iPhone/iPad dispute. Rich Media PDF will not operate in Apple's iOS devices such as the iPad and interactivity is limited.

'''Interactive Forms''' is a mechanism to add forms to the PDF file format.

PDF currently supports two different methods for integrating data and PDF forms. Both formats today coexist in PDF specification:<ref name="iso32000">{{citation |url=https://www.adobe.com/devnet/acrobat/pdfs/PDF32000_2008.pdf |title=Document Management – Portable Document Format – Part 1: PDF 1.7, First Edition |author=Adobe Systems Incorporated |date=2008-07-01 |accessdate=2010-02-19}}</ref><ref>{{cite web |url=http://gnupdf.org/Forms_Data_Format |title=Gnu PDF - PDF Knowledge - Forms Data Format |archiveurl=https://web.archive.org/web/20130101054615/http://www.gnupdf.org/Forms_Data_Format |archivedate=2013-01-01 |accessdate=2010-02-19}}</ref><ref>{{cite web |url=http://livedocs.adobe.com/coldfusion/8/htmldocs/help.html?content=formsPDF_02.html |title=About PDF forms |accessdate=2010-02-19}}</ref><ref>{{cite web |url=http://forums.adobe.com/thread/301733 |title=Convert XFA Form to AcroForm? |year=2008 |accessdate=2010-02-19}}</ref>
* '''AcroForms''' (also known as '''Acrobat forms'''), introduced in the PDF 1.2 format specification and included in all later PDF specifications.
* '''[[XML Forms Architecture|Adobe XML Forms Architecture]] (XFA)''' forms, introduced in the PDF 1.5 format specification. The XFA specification is not included in the PDF specification, it is only referenced as an optional feature. Adobe XFA Forms are not compatible with AcroForms.<ref>{{cite web |url=http://partners.adobe.com/public/developer/tips/topic_tip2.html |title=Migrating from Adobe Acrobat forms to XML forms |accessdate=2010-02-22}}</ref>

==== AcroForms ====
AcroForms were introduced in the PDF 1.2 format. AcroForms permit using objects (''e.g.'' [[text box]]es, [[Radio button]]s, ''etc.'') and some code (''e.g.'' [[JavaScript]]).

Alongside the standard PDF action types, interactive forms (AcroForms) support submitting, resetting, and importing data. The "submit" action transmits the names and values of selected interactive form fields to a specified uniform resource locator (URL). Interactive form field names and values may be submitted in any of the following formats, (depending on the settings of the action’s ExportFormat, SubmitPDF, and XFDF flags):<ref name="iso32000" />
* HTML Form format (HTML 4.01 Specification since PDF 1.5; HTML 2.0 since 1.2)
* Forms Data Format (FDF)
* XML Forms Data Format (XFDF) (external XML Forms Data Format Specification, Version 2.0; supported since PDF 1.5; it replaced the "XML" form submission format defined in PDF 1.4)
* PDF (the entire document can be submitted rather than individual fields and values). (defined in PDF 1.4)

AcroForms can keep form field values in external stand-alone files containing key:value pairs. The external files may use Forms Data Format (FDF) and XML Forms Data Format (XFDF) files.<ref>{{cite web |url=http://kb2.adobe.com/cps/325/325874.html |title=Using Acrobat forms and form data on the web |author=Adobe Systems Incorporated |date=2007-10-15 |accessdate=2010-02-19}}</ref><ref name="xfdf">{{citation |url=http://partners.adobe.com/public/developer/en/xml/xfdf_2.0.pdf |format=PDF |title=XML Forms Data Format Specification, version 2 |date=September 2007 |accessdate=2010-02-19}}</ref><ref name="fdf-exchange">{{citation |url=https://www.adobe.com/devnet/acrobat/pdfs/fdf_data_exchange.pdf |format=PDF |title=FDF Data Exchange Specification |date=2007-02-08 |accessdate=2010-02-19}}</ref> The usage rights (UR) signatures define rights for import form data files in FDF, XFDF and text ([[comma-separated values|CSV]]/[[delimiter-separated values|TSV]]) formats, and export form data files in FDF and XFDF formats.<ref name="iso32000" />

===== 表单数据结构（FDF） =====
{{Infobox file format
| name = Forms Data Format (FDF)
| icon =
| logo =
| screenshot =
| caption =
| extension = .fdf
| mime = application/vnd.fdf<ref>{{citation |url=http://www.iana.org/assignments/media-types/application/ |title=IANA Application Media Types - vnd.fdf |accessdate=2010-02-22}}</ref>
| type code = 'FDF'
| uniform type =
| magic =
| owner = [[Adobe Systems]]
| released = {{Start date|1996}}<!-- {{Start date|YYYY|mm|dd|df=yes}} --> (PDF 1.2)
| latest release version =
| latest release date = <!-- {{Start date and age|YYYY|mm|dd|df=yes}} -->
| genre =
| container for =
| contained by =
| extended from = PDF
| extended to = XFDF
| standard = ISO 32000-1:2008
| free = Yes
| url =
}}

The Forms Data Format (FDF) is based on PDF, it uses the same syntax and has essentially the same file structure, but is much simpler than PDF, since the body of an FDF document consists of only one required object. Forms Data Format is defined in the PDF specification (since PDF 1.2). The Forms Data Format can be used when submitting form data to a server, receiving the response, and incorporating into the interactive form. It can also be used to export form data to stand-alone files that can be imported back into the corresponding PDF interactive form. Beginning in PDF 1.3, FDF can be used to define a container for annotations that are separate from the PDF document they apply to. FDF typically encapsulates information such as [[X.509|X.509 certificates]], requests for certificates, directory settings, timestamp server settings, and embedded PDF files for network transmission.<ref name="fdf-exchange" /> The FDF uses the MIME content type application/vnd.fdf, filename extension .fdf and on Mac OS it uses file type 'FDF'.<ref name="iso32000" /> Support for importing and exporting FDF stand-alone files is not widely implemented in free or freeware PDF software. For example, there is no import/export support in Evince, Okular, Poppler, KPDF or Sumatra PDF, however, Evince, Okular and Popller support filling in of PDF Acroforms and saving filled data inside the PDF file. Import support for stand-alone FDF files is implemented in Adobe Reader; export and import support (including saving of FDF data in PDF) is for example implemented in Foxit Reader and PDF-XChange Viewer Free; saving of FDF data in a PDF file is also supported in pdftk.

===== XML表单数据结构（XFDF） =====
{{Infobox file format
| name = XML Forms Data Format (XFDF)
| icon =
| logo =
| screenshot =
| caption =
| extension = .xfdf
| mime = application/vnd.adobe.xfdf<ref>{{citation |url=http://www.iana.org/assignments/media-types/application/vnd.adobe.xfdf |title=IANA Application Media Types - Vendor Tree - vnd.adobe.xfdf |accessdate=2010-02-22}}</ref>
| type code = 'XFDF'
| uniform type =
| magic =
| owner = [[Adobe Systems]]
| released = {{Start date|2003|07|df=yes}} (referenced in PDF 1.5)
| latest release version = 3.0
| latest release date = {{Start date and age|2009|08|df=yes}}
| genre =
| container for =
| contained by =
| extended from = PDF, FDF, [[XML]]
| extended to =
| standard = No (under standardization as ISO/CD 19444-1<ref name="iso-xfdf">{{citation |url=http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?ics1=35&ics2=240&ics3=30&csnumber=64911 |title=ISO/CD 19444-1 - Document management - XML forms data format - Part 1: XFDF 3.0 |accessdate=2014-11-26}}</ref>)
| free =
| url = [https://partners.adobe.com/public/developer/en/xml/XFDF_Spec_3.0.pdf XFDF 3.0 specification]
}}

XML Forms Data Format (XFDF) is the XML version of Forms Data Format, but the XFDF implements only a subset of FDF containing forms and annotations. There are not XFDF equivalents for some entries in the FDF dictionary - such as the Status, Encoding, JavaScript, Pages keys, EmbeddedFDFs, Differences and Target. In addition, XFDF does not allow the spawning, or addition, of new pages based on the given data; as can be done when using an FDF file. The XFDF specification is referenced (but not included) in PDF 1.5 specification (and in later versions). It is described separately in ''XML Forms Data Format Specification''.<ref name="xfdf" /> The PDF 1.4 specification allowed form submissions in XML format, but this was replaced by submissions in XFDF format in the PDF 1.5 specification. XFDF conforms to the XML standard. As of November 2014, XFDF 3.0 is in the ISO/IEC standardization process under the formal name ''ISO/CD 19444-1 - Document management - XML forms data format - Part 1: XFDF 3.0''.<ref name="iso-xfdf"/>

XFDF can be used the same way as FDF; e.g., form data is submitted to a server, modifications are made, then sent back and the new form data is imported in an interactive form. It can also be used to export form data to stand-alone files that can be imported back into the corresponding PDF interactive form. A support for importing and exporting XFDF stand-alone files is not widely implemented in free or freeware PDF software. Import of XFDF is implemented in Adobe Reader 5 and later versions; import and export is implemented in PDF-XChange Viewer Free; embedding of XFDF data in PDF form is implemented in pdftk (pdf toolkit).

==== Adobe XML表单架构（XFA） ====
{{Main|XFA|l1=XML Forms Architecture}}
In the PDF 1.5 format, [[Adobe Systems]] introduced a new, proprietary format for forms, namely Adobe XML Forms Architecture (XFA) forms. The XFA 2.02 is referenced in the PDF 1.5 specification (and also in later versions) but is described separately in ''Adobe XML Forms Architecture (XFA) Specification'', which has several versions.<ref name="xfa-adobe">{{cite web |url=http://partners.adobe.com/public/developer/xml/index_arch.html |title=Adobe XML Forms Architecture (XFA) |author=Adobe Systems Incorporated |accessdate=2010-02-19}}</ref> XFA specification is not included in ISO 32000-1 PDF 1.7 and is only referenced as an external proprietary specification created by Adobe. XFA was not standardized as an ISO standard. In 2011 the ISO Committee (TC 171/SC 2/WG 8) urged Adobe Systems to submit the XFA Specification for standardization.<ref name="iso-meeting-n603" />

Adobe XFA Forms are not compatible with AcroForms. Adobe Reader contains "disabled features" for use of XFA Forms, that activate only when opening a PDF document that was created using enabling technology available only from Adobe.<ref>{{citation |url=https://www.adobe.com/products/eulas/pdfs/Reader_Player_AIR_WWEULA-Combined-20080204_1313.pdf |format=PDF |title=Adobe Reader - Software license agreement |accessdate=2010-02-19}}</ref><ref>{{cite web |url=https://www.adobe.com/go/readerextensions |title=LiveCycle Reader Extensions ES features and benefits |accessdate=2010-02-19}}</ref> The XFA Forms are not compatible with Adobe Reader prior to version 6.

XFA forms can be created and used as PDF files or as XDP ([[XML Data Package]]) files. The format of an XFA resource in PDF is described by the XML Data Package Specification.<ref name="iso32000" /> The XDP may be a standalone document or it may in turn be carried inside a PDF document. XDP provides a mechanism for packaging form components within a surrounding XML container. An XDP can also package a PDF file, along with XML form and template data.<ref name="xfa-adobe" /> PDF may contain XFA (in XDP format), but also XFA may contain PDF.<ref name="xfa-adobe" /> When the XFA (XML Forms Architecture) grammars used for an XFA form are moved from one application to another, they must be packaged as an XML Data Package.<ref name="xfa25">{{citation |url=http://partners.adobe.com/public/developer/en/xml/xfa_spec_2_5.pdf |format=PDF |title=XML Forms Architecture (XFA) Specification Version 2.5 |date=2007-06-08 |accessdate=2010-02-19}}</ref>

When the PDF and XFA are combined, the result is a form in which each page of the XFA form overlays a PDF background. This architecture is
sometimes referred to as XFAF (XFA Foreground). The alternative is to express all of the form, including boilerplate, directly in XFA (without using PDF, or only using "Shell PDF" which is a container for XFA with minimal skeleton of PDF markup, or using a pre-rendered depiction of a static XFA form as PDF pages). It is sometimes called ''full'' XFA.<ref name="xfa25" />

Starting with PDF 1.5, the text contents of variable text form fields, as well as markup annotations may include formatting information (style information). These rich text strings are XML documents that conform to the rich text conventions specified for the XML Forms Architecture specification 2.02, which is itself a subset of the XHTML 1.0 specification, augmented with a restricted set of CSS2 style attributes.<ref name="iso32000" />
In PDF 1.6, PDF supports the rich text elements and attributes specified in the XML Forms Architecture (XFA) Specification, 2.2.
In PDF 1.7, PDF supports the rich text elements and attributes specified in the XML Forms Architecture (XFA) Specification, 2.4.<ref name="iso32000" />

Most PDF processors do not handle XFA content. When generating a shell PDF it is recommended to include in the PDF markup a simple one-page PDF image displaying a warning message (e.g. "To view the full contents of this document, you need a later version of the PDF viewer.", etc.). PDF processors that can render XFA content should either not display the supplied warning page image or replace it quickly with the dynamic form content.<ref name="xfa33" /> Examples of PDF software with some support of XFA rendering include Adobe Reader for Windows, Linux, Mac OS X (but not Adobe Reader Mobile for Android or iOS) or Nuance PDF Reader.

=== 逻辑构造与可读性 ===

A "tagged" PDF (ISO 32000-1:2008 14.8) includes document structure and semantics information to enable reliable text extraction and accessibility. Technically speaking, tagged PDF is a stylized use of the format that builds on the logical structure framework introduced in PDF 1.3. Tagged PDF defines a set of standard structure types and attributes that allow page content (text, graphics, and images) to be extracted and reused for other purposes.<ref>[http://www.planetpdf.com/enterprise/article.asp?ContentID=6067 What is Tagged PDF?]</ref>

Tagged PDF is not required in situations where a PDF file is intended only for print. Since the feature is optional, and since the rules for Tagged PDF as specified in ISO 32000-1 are relatively vague, support for tagged PDF amongst consuming devices, including assistive technology (AT), is uneven.<ref>[http://www.washington.edu/doit/Stem/articles?1002 Is PDF Accessible?]</ref>

An [[AIIM]] project to develop an ISO-standardized subset of PDF specifically targeted at accessibility began in 2004, eventually becoming [[PDF/UA]].

=== 安全和签名 ===

A PDF file may be encrypted for security, or digitally signed for authentication.

The standard security provided by Acrobat PDF consists of two different methods and two different passwords, ''user password'', which encrypts the file and prevents opening, and ''owner password'', which specifies operations that should be restricted even when the document is decrypted, which can include: printing, copying text and graphics out of the document, modifying the document, or adding or modifying text notes and [[Acroforms|AcroForm]] fields. The user password (controls opening) encrypts the file and requires [[password cracking]] to defeat, with difficulty depending on password strength and encryption method – it is potentially very secure (assuming good password and encryption method without known attacks). The owner password (controls operations) does not encrypt the file, and instead relies on client software to respect these restrictions, and is not secure. An "owner password" can be removed by many commonly available "PDF cracking" software, including some free online services.<ref>[http://freemypdf.com/ FreeMyPDF - A website that removes PDF user password restrictions]</ref> Thus, the use restrictions that a document author places on a PDF document are not secure, and cannot be assured once the file is distributed; this warning is displayed when applying such restrictions using Adobe Acrobat software to create or edit PDF files.

Even without removing the password, most freeware or open source PDF readers ignore the permission "protections" and allow the user to print or make copy of excerpts of the text as if the document were not limited by password protection.

Some solutions, like Adobe's LiveCycle Rights Management, are more robust means of information rights management, which can not only restrict who can open documents but also reliably enforce permissions in ways that the standard security handler does not.

==== 使用权 ====
Beginning with PDF 1.5, Usage rights (UR) signatures are used to enable additional interactive features that are not available by default in a particular PDF viewer application. The signature is used to validate that the permissions have been granted by a bonafide granting authority. For example, it can be used to allow a user:<ref name="iso32000" />
* to save the PDF document along with modified form and/or annotation data
* import form data files in FDF, XFDF and text (CSV/TSV) formats
* export form data files in FDF and XFDF formats
* submit form data
* instantiate new pages from named page templates
* apply a [[Digital data|digital]] [[signature]] to existing [[digital signature]] form field
* create, delete, modify, copy, import, export annotations

For example, Adobe Systems grants permissions to enable additional features in Adobe Reader, using public-key [[cryptography]]. Adobe Reader verifies that the signature uses a [[Public key certificate|certificate]] from an Adobe-[[authorize]]d certificate authority. The PDF 1.5 specification declares that other PDF viewer applications are free to use this same mechanism for their own purposes.<ref name="iso32000" />

=== 文件附件 ===

PDF files can have document-level and page-level file attachments, which the reader can access and open or save to their local filesystem. PDF attachments can be added to existing PDF files for example using [[pdftk]]. Adobe Reader provides support for attachments, and [[poppler (software)|poppler]] based readers like [[Evince]] or [[Okular]] also have some support for document-level attachments.

=== 元数据 ===
PDF files can contain two types of metadata.<ref>[https://www.adobe.com/devnet/acrobat/pdfs/pdf_reference_1-7.pdf Adobe PDF reference version 1.7], section 10.2</ref> The first is the Document Information Dictionary, a set of key/value fields such as author, title, subject, creation and update dates. This is stored in the optional Info trailer of the file. A small set of fields is defined, and can be extended with additional text values if required.


Later, in PDF 1.4, support was added for the Metadata Streams, using the [[Extensible Metadata Platform]] (XMP) to add XML standards-based extensible metadata as used in other file formats. This allows metadata to be attached to any stream in the document, such as information about embedded illustrations, as well as the whole document (attaching to the document catalog), using an extensible schema.
{{transF}}
== 内容 ==
== 内容 ==
PDF文件通常混合了[[矢量图形]]、文本和[[位图]]。PDF的基本内容包括：
PDF文件通常混合了[[矢量图形]]、文本和[[位图]]。PDF的基本内容包括：

2015年1月20日 (二) 04:23的版本

[[Category:需要從{{ISO 639 name en:Portable Document Format}}維基百科翻譯的條目]][[Category:需要從{{ISO 639 name en:Portable Document Format}}維基百科翻譯的條目]]

  关于英文縮寫為PDF的數學函數，請見「機率密度函數」。
便攜式文件格式（PDF）
扩展名
.pdf
互联网媒体类型
application/pdf,[1] application/x-pdf, application/x-bzpdf, application/x-gzpdf
类型代码（英语：Type code）'PDF '[1]（包含一个空格）
统一类型标识com.adobe.pdf
开发者Adobe Systems
首次发布1993年 (1993)
最新版本
1.7
扩展为PDF/A、PDF/E、PDF/UA、PDF/VT、PDF/X
标准ISO 32000
免费格式？是
网站www.adobe.com/devnet/pdf/pdf_reference_archive.html

PDF（Portable Document Format的簡稱，意為「便攜式文件格式」）是由Adobe Systems用於與應用程式、硬體、作業系統無關的方式進行文件交換所發展出的文件格式。[2]每個PDF文件包含固定布局的平面文檔的完整描述，包括文本、字形、圖形及其他需要顯示的資訊。1991年，Adobe Systems共同創始人John Warnock提出的名為“Camelot”的系統[3]演變成PDF。

在Adobe Systems决定PDF规范在1993年可以自由使用的时候，PDF是由Adobe控制的专有格式（英语：proprietary format），直到2008年7月1日官方作为开放标准发行，并由国际标准化组织以ISO 32000-1:2008标准发布，[4][5]在这段时间规范通过ISO志愿者产业专家委员会控制。2008年，Adobe发布对ISO 32000-1的公共专利许可赋予对所有Adobe拥有的制作、使用、销售及分发兼容PDF的实现所需的专利的自由授权的权益。[6]然而仍有一些ISO 32000-1所引用的可以被纳入有效的PDF文件的技术保持专有（但仍是公开记录），如Adobe XML表单架构，以及JavaScript for Acrobat。[7][8][9][10][11]ISO委员会正活跃地制定许多这类的标准作为ISO 32000-2的一部分。

歷史

PDF檔案格式在1990年代早期開發，以作為能夠包括文件的格式、內建影像的分享方法，而且能夠跨平台操作，即使完全不同的電腦平台之上收件者未必有相關或合用的應用軟體接口可使用[12]。當時與PDF一起競逐跨平台檔案格式的，還包括DjVu（仍在開發中）、Envoy、Common Ground Digital Paper、Farallon Replica及Adobe自己本身的PostScript（.ps）格式。在當時萬維網及HTML文本尚未興起之時的最初幾年中，PDF在桌面出版工作流技术當中很受歡迎。

PDF在早期文件格式分享歷史的接受程度頗晚。[13]可以閱讀及產生PDF格式的程式Adobe Acrobat並非免費產品；早期版本的PDF也不支持外部連結，使之在互聯網上的可用性減低；相較於全文本的格式顯得很巨大的PDF檔案，在當時仍然要利用modem來連線的年代需要更長的下載時間，再者以當年性能低的電腦要渲染PDF檔的過程也超慢。

從2.0版開始，Adobe開始免費分發PDF的閱讀軟件Acrobat Reader（現時改稱Adobe Reader，建立軟件依然稱為Adobe Acrobat）[14]，而舊的格式依舊支援，使PDF後來成為固定格式文本業界的非正式標準（英语：de facto standard）[15]。

及至2008年，Adobe Systems的PDF參考1.7版成為了ISO 32000:1:2008，從此PDF就成為了正式的國際標準。亦因為這個緣故，現時PDF的更新版本開發（包括未來的PDF 2.0版本的開發）變成由ISO的TC 171 SC 2 WG 8主導，但Adobe及其他相關項目的專家依然有參與其中。

Adobe规范

从1993-2006年Adobe Systems数次更改PDF规范并添加新特性。2006和发布的各个方面的Adobe的扩展层被采纳为ISO 32000-2（PDF 2.0）的工作草案，但开发者注意到Adobe的扩展不是PDF标准的一部分。[16]

版本号 版本[4] 发布年份 新特性 Acrobat Reader支持版本
1.0 第一版 1993 Carousel
1.1 第一版修订 1996 密码、加密（MD5、RC4 40bit）、独立于设备的颜色、线程和链接[17] 2.0
1.2 第一版修订 1996 交互式页面元素（单选按钮、复选框等）；交互式、填入式的表单（AcroForm）；适用于可以从Web导入、导出、传送及接收的交互式表单数据的表单数据格式（Forms Data Format，FDF）；鼠标事件；外部影片录制；外部或内嵌声音录制；二进制数据的zlib/deflate压缩；Unicode；高级颜色特性及图像代理[17] 3.0
1.3 第二版 2000 数字签名；ICC及DeviceN颜色空间；JavaScript动作；嵌入任意类型的文件流（例如用于附件）；新的注释格式；新的Adobe PostScript Language Level 3成像模型特性；遮罩图像；图像的替代性表现；平滑阴影；增强式页码；Web截取，用于从万维网截取信息并转换为PDF的能力；图形结构的逻辑性结构独立的呈现；对CID字体的附加支持；用于映射字符串及PDF对象编号的数据结构；印前生产流程支持的相关信息；一些呈现功能的参数化的类别的功能对象的新特性；[18][19] Acrobat Forms JavaScript Object Specification 4.05版 4.0
1.4 第三版 2001 JBIG2；透明度；长度大于40位（40–128位）的RC4加密密钥；对交互式表单及表单数据格式（FDF）、XML表单提交、嵌入式FDF文件、 字段输出值的Unicode规格、远程协作和FDF文件中的数字签名的改进；被禁用户的可访问性；使用可扩展元数据平台（XMP）的元数据流；加标记的PDF；打印者标记的包含；生产相关的页面边界的显示及预览；新预定义的CMaps；替代性呈现；从一个PDF文档到另一个文档导入内容；PDF文档的命名词典中的EmbeddedFiles词条，嵌入数据的标准方位；[19][20]Acrobat Forms JavaScript Object Specification 4.05版[21] 5.0
1.5 第四版 2003 JPEG 2000；对多媒体嵌入及后端的增强的支持；对象流；跨引用流；XML表单数据格式（XML Forms Data Format，XFDF）用于交互式表单提交（PDF 1.4中取代XML格式）；support for 表单、富文本元素与基于Adobe XML表单架构（英语：XML Forms Architecture）（XFA）2.02的属性（只定义静态XFA表单）；使用PKCS#7的公共密钥安全处理器（PDF 1.3引入，但没在参考书中记录，直到1.5）、公共密钥加密、权限、使用权（UR）签名（不要求文档加密）、带SHA-1的PKCS#7、RSA扩大到4096位；安全处理器可以使用自身的加密和解密算法；文档章节通过作者或读者以诸如CAD图画、分层（英语：layers (digital image editing)）插图、地图和多语言文档之类的项选择性的查看或隐藏；交替呈现——仅幻灯片一种类型——由JavaScript动作的方式（Adobe Reader仅支持SVG 1.0）产生；[19][22][23] Acrobat JavaScript Scripting Reference，6.0版；[24]对微软Windows 98拖放的支持。 6.0
1.6 第五版 2004 3D艺术，如对Universal 3D文件格式的支持；OpenType字体嵌入；对XFA 2.2富文本元素及属性（XFA 2.1及2.2定义以下列特性为例：动态XFA表单，XFA的W3C XML数字签名，针对网络服务的XFA支持，HTTP之上的XFA“文档逐字的”SOAP操作，网络服务的WSDL定义SOAP绑定操作等）的支持；AES加密；带SHA256的PKCS#7，DSA升到4096位；NChannel颜色空间；嵌入式附件的附加支持，包括跨文档链入及来自嵌入的文件；增强和澄清数字签名相关的使用权和修改检测及阻止签名；[19] Acrobat JavaScript Scripting Reference，7.0版[25] 7.0
1.7
（ISO 32000-1:2008
[4][26]）		 第六版（ISO第一版） 2006（ISO 2008） 增加3D艺术的呈现；XFA 2.4富文本元素及属性；多附件（便携式收集）；PDF消费者应用的文档要求；新字符串类型：PDFDocEncoded字符串、ASCII字符串、字节字符串；带SHA384、SHA512和RIPEMD160的PKCS#7；JavaScript for Acrobat API Reference 8.0版（适用于Adobe Acrobat Professional、Acrobat Standard和Adobe Reader的JavaScript扩展的对象、属性及算法的文档）[27] 8
1.7 Adobe Extension Level 1[28] 2008 XFA 2.5（Extensions Level 1）和XFA 2.6（Extensions Level 2）（XFA 2.6定义如下所示：XFA安全提交，新的配置文件——XFA前景色（XFAF）——每个XFA表单的页面覆以PDF背景等）[29] 8.1
1.7 Adobe Extension Level 3 2008 256为AES加密；XFA数据集并入符合PDF/A-2标准的文件；对Adobe Flash应用（SWF）、视频（含H.264编码的Flash视频）、音频及其他多媒体、Flash player和整合应用之间的双向脚本桥接、可能以Adobe Flex 2模块或者作为普通SWF加载的导航SWF附件的改进；XFA 2.5与2.6富文本协定，[29]XFA 2.7与2.8[30]（XFA 2.7与2.8定义如下所示：用于网络服务的认证策略，通过WSDL/SOAP提交，按区域设置字体等） 9
1.7 Adobe Extension Level 5[31] 2009 XFA 3.0 9.1
1.7 Adobe Extension Level 6[32] 2009 XFA 3.1 9.1
1.7 Adobe Extension Level 8[33] 2011 XFA 3.3（如Flash/SWF整合进XFA），[34]比Extension Level 3不同的AES-256密码处理，因为密码测试算法的虚弱。[35][36]规格截至2014年11月未出版。[26] X (10)

ISO标准ISO 32000-1:2008及Adobe PDF 1.7在技术上是相容的。[26][37][38]Adobe宣称没有制定PDF 1.8参考。PDF规格的未来版本将由ISO技术委员会制定。然而，Adobe出版的文档指明什么是PDF的专有扩展功能，ISO 32000-1（PDF 1.7）之外的在新发布的产品中支持。这利用了如同在Annex E中ISO 32000-1中记录的PDF的扩展性特性。[26]

PDF规格包容性滞后。PDF 1.7规格包括了所有先前的功能性的Adobe PDF规格1.0到1.6版的记录。在那里Adobe从他们的标准删除了PDF的某些特性，那些没被包含在ISO 32000-1[4]。一些特性被标为落后的。

PDF文档遵循带有PDF 1.7版的ISO 32000-1标准。包含了Adobe扩展的特性仍带有PDF基础版本号1.7的文档也包含随着文档的创建扩展的指示。[26]

ISO标准化

自1995起，Adobe参与了一些由ISO创建出版技术规范及在用于特定行业及用途的PDF标准专业子集（如PDF/X或PDF/A）进程中与ISO协作的工作组。[39]制定完整PDF规格的子集的目的是移除那些不需要或会对特定用途造成问题以及一些要求的功能的使用在完整PDF规格中仅仅是可选的（不是强制性的）功能。

2007年1月29日，Adobe宣布将发布完整的PDF 1.7规格给美国国家标准协会（ANSI）及企业内容管理协会（AIIM），为了由国际标准化组织(ISO)发布。[39]ISO将制定PDF规格是未来版本，而且Adobe仅仅是ISO技术委员会的一员。[26]

ISO“全功能PDF”的标准[39]在正式编号ISO 32000之下发布。全功能PDF规格意味着不仅仅是Adobe PDF规格的子集；就ISO 32000-1而言全功能PDF包含了Adobe的PDF 1.7规格定义的每一条。然而，Adobe后来发布了不是ISO标准的一部分的扩展。[26]那些也是PDF规格中的专有功能，只能作为额外的规格参考。[8][10]

PDF标准化的子集

下列指定的PDF规格的子集被定为ISO标准（或者在标准化过程当中）：[4][40][41][42]

  • PDF/X（2001年起—ISO 15929及ISO 15930系列标准的一部分）又叫“PDF for Exchange”——用于“图形技术——印刷前数据交换”——（ISO技术委员会130的工作），基于PDF 1.3、PDF 1.4还有后来的PDF 1.6
  • PDF/A（2005年起—ISO 19005系列标准的一部分）又叫“PDF for Archive”——“文档管理——用于长期保存的电子文档文件格式”（ISO技术委员会171的工作），基于PDF 1.4还有后来的ISO 32000-1 - PDF 1.7
  • PDF/E（2008年起—ISO 24517）又叫“PDF for Engineering”——“文档管理——使用PDF的工程文档格式”（ISO技术委员会171的工作），基于PDF 1.6
  • PDF/VT（2010年起—ISO 16612-2）又叫“PDF for exchange of variable data and transactional (VT) printing”——“图形技术——可变数据交换”（ISO技术委员会130的工作），基于PDF 1.6并受限于PDF/X-4及PDF/X-5[43]
  • PDF/UA（2012年起—ISO 14289-1）又叫“PDF for Universal Accessibility”——“文档管理应用——可访问的电子文档文件格式”（ISO技术委员会171的工作），基于ISO 32000-1 - PDF 1.7

还有PDF/H，也就是“PDF Healthcare”，最佳措施导览（Best Practices Guide，BPG），通过实施指南（Implementation Guide，IG）增补，2008年发布。PDF Healthcare不是一个标准或者推荐标准，但仅仅是一个使用已有标准及其他技术的指南。受到标准发展机构ASTM与AIIM支持。PDF/H BPG基于PDF 1.6。[44][45][46]

PDF 1.7

PDF 1.7的最终修订的文档由ISO技术委员会171于2008年1月认可，并以ISO 32000-1:2008发布于2008年7月1日，题为“Document management – Portable document format – Part 1: PDF 1.7”。

ISO 32000-1:2008是第一份全功能PDF的ISO标准。先前的ISO PDF标准（PDF/A、PDF/X等）用于更特殊的用途。ISO 32000-1包括了所有先前的功能性的Adobe PDF规格1.0到1.6版的记录。Adobe从先前的版本中移除了某些PDF特性；这些特性也没包含在PDF 1.7中。[4]

ISO 32000-1文档由Adobe Systems Incorporated基于《PDF Reference, sixth edition, Adobe Portable Document Format version 1.7, November 2006》准备的。在一个特殊的快速进程下检验、修订并接受，通过《ISO Technical Committee 171 (ISO/TC 171), Document management application, Subcommittee SC 2, Application issues》，与ISO成员的提议并行。

根据ISO PDF标准：[47]

ISO 32000-1:2008指定独立于他们创建的环境或他们查看、阅读的环境的用于呈现电子文档的数码形式以使用户交换并查看电子文档。该标准用于创建PDF文件的软件的开发者（相应的作者）、阅读已有PDF文件及解释其内容以显示和协作的软件（相应的读者）以及用于其他多种目的阅读和/或编写PDF文件的PDF产品（相应的产品）。

一些Adobe Systems控制下的专属的规格（如Adobe Acrobat JavaScript或XML表单架构）处于ISO 32000-1规范性参考中，而且对于ISO 32000-1标准的应用不可或缺。[39]

PDF 2.0

PDF标准的新版本以ISO/CD 32000-2 - Document management – Portable document format – Part 2: PDF 2.0的名义下开发（截至2013年8月）。[48][49]PDF 2.0被ISO作为新提议于2009年采纳（ISO/NP 32000-2）。TC 171 SC 2 WG 8委员会的ISO 32000-2（PDF 2.0）制定工作正在持续以积极开发文档；处理数以百计的技术和编辑上的建议，并管理由多个当事人（包括Adobe Systems）组成的八个特设委员会。为提供更多时间以开发文档，原来的ISO项目于2012年撤销（作为“国际标准草案”处于调查阶段），并启动新项目。[48][49][50]

Adobe提交了《Adobe Extension Level 5》和《Adobe Extension Level 3》规格给ISO以纳入ISO 32000-2规格，但只有其中一部分特性被采纳。

ISO委员会开发PDF 2.0的目标包括了进一步的增强、PDF语言的改进、去除不再使用的特性（如Form XObject名称）与Adobe专有的规格的标准化（如Adobe JavaScript、Rich Text）。[10][51]

PDF 2.0将参考Adobe的XML表单架构3.1。2011年ISO委员会强烈要求Adobe Systems提交XFA规格给ISO用以标准化并要求Adobe Systems保持XFA规格的稳定。ISO表示担心XFA规格的稳定性。[8]

ISO TC 171 SC 2 WG 8

成立于2008年以策划PDF参考书作为ISO标准的Working Group 8通常一年召开两次会议，来自十多个国家的成员在每个实例中参与。ISO委员会关于ISO 32000的会议向受到学科问题专家认可的人开放。有兴趣的人一方会为有关参与ISO 32000的信息联系各自的ISO成员体。

当前的项目领导人：Cherie Ekholm、微软及项目联合领导人、独立顾问Duff Johnson[52]

过去的项目领导人：2008-2011：James King，PhD、Adobe Systems

ISO秘书处：Betsy Fanning，AIIM

GB标准化

2009年9月1日，作为电子文档长期保存格式的PDF/Archive（PDF/A）经中国国家标准化管理委员会批准已成为正式的中华人民共和国国家标准（GB）[53]，标准号为GB/T 23286.1-2009[54]。

技术基础

任何人可以创建能阅读和编写PDF而不需要给Adobe Systems支付版税的应用；Adobe对PDF持有专利，但以自由授权（Royalty-free）的方式许可使用于开发遵从PDF规格的应用。[55]

PDF主要由三項技術組成：

  • 衍生自PostScript的頁面描述語言子集，用以生成和輸出圖形。
  • 字型嵌入/替換系統，可使字型隨文件一起傳輸。
  • 結構化的存儲系統，用以綁定這些元素和任何相關内容到單個檔案，帶有適當的資料壓縮系統。

内容

PDF文件通常混合了矢量图形、文本和位图。PDF的基本内容包括：

  • 文本存储为内容字符串（就是不是文本本身）
  • 由图形和线条组成的用于说明和设计的矢量图形
  • 由相片和其他类型的图片组成的位图

在近期PDF标准修订中，PDF文档还支持链接（文档内部或网页）、表单、JavaScript（可通过Acrobat 3.0的插件启用），或者其他任意类型的能用插件控制的可嵌入内容。

PDF 1.6支持互动式3D文档嵌入PDF——3D绘图可用U3D或PRC及其他多种格式嵌入。[81][82]

在电脑屏幕上看起来相似的两个PDF文件有可能大小不同。例如，一个高分辨率位图比低分辨率的占更多的存储空间。通常更高的分辨率更适宜打印文档而不是显示与屏幕。其他可能影响文件大小的可能有嵌入全部字体，尤其是东亚字体，以及将文字存为图片。

PDF工具

参见：PDF軟體列表

参考文献

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