本规范称为EPUB规范片段标识符（epubcfi），定义了通过使用片段标识符引用EPUB？出版物中任意内容的标准化方法。 网络已经证明了超链接的概念是非常强大的，但EPUB出版物由于缺乏一个标准化的链接方案而无法获得超链接带来的许多好处。尽管已经为各个阅读系统开发和实施了专有方案，但如果没有一种普遍理解的语法，就无法实现跨平台的互操作性。然而，打破这一障碍可以带来显著好处的功能是多种多样的:从阅读位置维护到注释附件再到导航，指向任何出版物的能力打开了一个开发人员和作者以前无法使用的全新维度。 本规范试图通过定义任意结构来纠正这种情况 可以唯一标识EPUB出版物中任何位置或简单位置范围的引用:EPUB CFI。以下考虑因素强烈影响了该方案的设计和范围: 用于引用内容的机制应该是可互操作的:对一个阅读系统创建的阅读位置的引用应该可以被另一个阅读系统使用。 对EPUB内容的文档引用的启用方式应与现有超链接在整个Web上启用引用的方式相同。 EPUB文件中的每个位置都应该能够识别，而无需修改文档。 所有引用相同逻辑位置的片段标识符在比较时应该相等。 比较操作，包括排序和比较测试，应该能够在不访问引用文件的情况下执行。 在不访问原始文件的情况下，应该可以进行简单的操作（例如，给定文件深处的引用，应该可以生成文件开头的引用）。 标识符解析应该合理有效（例如，解析指向最后一章的片段标识符不需要处理第一章）。 引用应该能够通过解析器变体和文档修订来恢复其目标位置。 应支持简单连续范围的表达式。 应提供一种可扩展的机制，以适应未来的参考恢复启发。 对于标准EPUB CFI和出版物内EPUB CFI，本规范符合W3C在第6节中表达的指南。Fragid结构的最佳实践[Fragid最佳实践]。 换句话说，两种标准CFI URI（例如，“book.epub#epubcfi（？）），参考媒体类型“application/epub+zip”）和出版物内CFI URI（例如，“package.opf#epubcfi（？），引用的媒体类型“application/oebps package+xml”）使用片段标识符语法，该语法在上述媒体类型的后缀注册（即“-xml”和“zip”）的上下文中不与现有方案重叠。

This specification, EPUB Canonical Fragment Identifier (epubcfi), defines a standardized method for referencing arbitrary content within an EPUB？ Publication through the use of fragment identifiers. The Web has proven that the concept of hyperlinking is tremendously powerful, but EPUB Publications have been denied much of the benefit that hyperlinking makes possible because of the lack of a standardized scheme to link into them. Although proprietary schemes have been developed and implemented for individual Reading Systems, without a commonly-understood syntax there has been no way to achieve cross-platform interoperability. The functionality that can see significant benefit from breaking down this barrier, however, is varied: from reading location maintenance to annotation attachment to navigation, the ability to point into any Publication opens a whole new dimension not previously available to developers and Authors. This specification attempts to rectify this situation by defining an arbitrary structural reference that can uniquely identify any location, or simple range of locations, in an EPUB Publication: the EPUB CFI. The following considerations have strongly influenced the design and scope of this scheme: The mechanism used to reference content should be interoperable: references to a reading position created by one Reading System should be usable by another. Document references to EPUB content should be enabled in the same way that existing hyperlinks enable references throughout the Web. Each location in an EPUB file should be able to be identified without the need to modify the document. All fragment identifiers that reference the same logical location should be equal when compared. Comparison operations, including tests for sorting and comparison, should be able to be performed without accessing the referenced files. Simple manipulations should be possible without access to the original files (e.g., given a reference deep in a file, it should be possible to generate a reference to the start of the file). Identifier resolution should be reasonably efficient (e.g., processing of the first chapter is not necessary to resolve a fragment identifier that points to the last chapter). References should be able to recover their target locations through parser variations and document revisions. Expression of simple, contiguous ranges should be supported. An extensible mechanism to accommodate future reference recovery heuristics should be provided. In the case of both Standard EPUB CFIs and Intra-Publication EPUB CFI, this specification conforms with the guidelines expressed by W3C in Section 6. Best Practices for Fragid Structures [FragIDBestPractices]. In other words, both standard CFI URIs (e.g., "book.epub#epubcfi(?)", referred media type "application/epub+zip") and intra-publication CFI URIs (e.g., "package.opf#epubcfi(?)", referred media type "application/oebps-package+xml") make use of a fragment identifier syntax that does not overlap with existing schemes in the context of the aforementioned media types' suffix registrations (i.e., "-xml" and "zip").