PDF格式给标准的重要性提供了一个很好的例证。如果在1993年,有关PDF的规范没有刊登在技术入门介绍中,PDF现在可能只是众多文档格式之一。各种机缘巧合之下,Adobe决定让用户免费获取PDF规范,这一决定推动了制定人员生态系统。
Adobe的PDF 1.7版在2008年成为ISO32000标准。此后, ISO/TC 171/SC 2/WG 8成员,负责规范标准的工作组,一直不断地完善这一规范。最近新发布的版本定为PDF2.0。
PDF的价值重大–PDF之所以成为全世界电子文件的事实标准,关键在于标准化本身。PDF文件应该是完全自足性的,相互之间可以编辑操作的文件。任何一家供应商提供的PDF软件都可以进行同样的操作和编辑。终端用户不管用什么软件编辑都可以获得一样的操作结果。PDF文件的呈现形式和操作功能是不变的,这一核心特点是该科技获得成功的主要原因。
PDF2.0版本的基本功能没有变化,但是PDF的使用价值有所提高。可能这个最重要的改进也是最小的一个改变。PDF2.0版本解决了模糊、错误修正的问题,一些特点更具现代化,更新了引用标准和六条关键条款。长达972页的规范中总计有14%的内容完全改写。
尽管这些改变不是什么新特点,但是用户可以更好地理解和实施这些规范,系统的互操作性更加完善。简单来说,制定人员可以以更简单的方式、更少的花费,在各个层次更好地改善对PDF的支持。
除了对现有规范的改进,PDF2.0也有一些全新的特点:
未经加密的打包文件允许在可读的“附信”文档内部传输可靠的PDF文件。
支持丰富的媒体注释,地理信息特征和PRC一种3D格式。
首次以PDF/A-3格式引入的相关文件,现在可以扩展到任意的PDF2.0文档,其中包括机器可读的PDF附件的元数据。
用户从提升的性能中获取资料、数据和其他的文件格式作为其PDF文件的一部分。
有关标签PDF的条款14.8已经彻底改写,取而代之的是一个改进的标签集,支持命名空间、数学标记语言和发音提示。这样一来更容易进行文章提取的重新建构,转换成适用于小型设备的超文本置标语言和其他的一些操作。
数字签名功能也更新了,符合最新的规范要求。用户在核对数字签名文档时可以有新的选择。
PDF现在可以支持256字节的AES加密,这是一条现行标准。
ISO 32000- 2,文件管理-便携式文档格式-第2部分:PDF 2.0,是第一个完全在ISO指导方针和过程要求规范内中开发的PDF规范。它更清晰、更整洁、支持非专利技术,并为软件供应商提供了一个公平的竞争环境,这些软件供应商可以创建、显示、编辑或以其他方式处理PDF电子文档。除了保持PDF的核心价值之外,PDF 2.0还为新的用例、功能和工作流提供了坚实的基础。
ISO 32000-2 标准是由ISO/TC 171技术委员会制定的,有关文件管理应用,SC 2专门小组,文档文件样式,电子文档管理系统(EDMS)和管理信息真实性的标准。ISO/TC 171技术委员会的秘书处是由美国国家标准学会(以下简称,ANSI)担任的,ANSI也是美国在ISO的成员组织。
The worldwide standard for electronic documents is evolving
The PDF format exemplifies the value of standards. Had the specification for PDF not been published from the technology’s introduction in 1993, PDF would just be one of a dozen document formats. More than any other single factor, Adobe’s decision to make the PDF specification freely available enabled an ecosystem of developers.
Adobe’s PDF version 1.7 became ISO 32000 in 2008. Since then, members of ISO/TC 171/SC 2/WG 8, the working group responsible for the standard, have continued the development of the specification, with the just-published version defined as PDF 2.0.
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PDF’s value proposition – the reason why PDF is today’s worldwide de facto standard for electronic documents – is the fact of standardization itself. PDF files are supposed to be entirely self-contained and interoperable, working equally well with PDF software from every vendor. End-users should be able to gain equivalent results irrespective of their choice of software. This core feature – PDF files always look and work the same way – is the dominant reason for the technology’s success.
In PDF 2.0, the fundamentals of PDF remain identical, but the value to users has increased. Perhaps the most important enhancement is also the most subtle. PDF 2.0 addresses ambiguities, corrects errors, modernizes many features, updates normative references and six critical clauses, totalling 14 % of the 972-page specification that were entirely rewritten.
Although these changes aren’t new features, they make it easier to understand and successfully implement the specification, with better interoperability. In short, PDF 2.0 will make it easier and less costly for developers to improve their support for PDF at every level.
PDF 2.0 does, however, include many entirely new features in addition to the improvements to the existing specification:
Unencrypted wrapper documents allow secured PDF files to be delivered inside a readable “cover letter” document.
There’s new support for rich media annotations, geospatial features and PRC, a 3D format.
Associated files, first introduced with PDF/A-3, now extend to any PDF 2.0 document the ability to include machine-readable metadata about files attached to the PDF.
Users gain from an enhanced ability to include source, data and other file formats as part of their PDF document.
Clause 14.8 on tagged PDF has been completely overhauled with a revised tag set, support for namespaces, MathML support and pronunciation hints. The result will be more accessible documents that are also much easier to repurpose for text extraction, conversion to HTML for small devices, and more.
Digital signature features have been updated to meet the latest specifications, allowing users new options for verifying digitally signed PDF documents.
PDF now supports 256-bit AES encryption, a current-generation standard.
ISO 32000-2, Document management – Portable document format – Part 2: PDF 2.0, is the first PDF specification developed entirely within the ISO guidelines and process. It’s clearer, cleaner, supports non-proprietary technologies and ensures a level playing field for software vendors that create, display, edit or otherwise process PDF electronic documents. In addition to staying true to PDF’s core value, PDF 2.0 provides a solid foundation for new use-cases, capabilities and workflows.
ISO 32000-2 was developed by technical committee ISO/TC 171, Document management applications, subcommittee SC 2, Document file formats, EDMS systems and authenticity of information, whose secretariat is held by ANSI, the ISO member for the United States.