7.21. Common attributes
- href
- Specifies the location of an input HTML file. This file must contain
      valid XHTML5
      (more information in Section 6.1. Valid XHTML5). The specified URL may not have a fragment identifier (e.g. something like href="ch09.html#conclusion"is not supported).
- pagename
- Specifies the base name without any extension of an output HTML
      file. By default, this name is the same as the name of the corresponding
      input HTML file. Example:<chapter href="intro.html" pagename="introduction"/> By default, without attribute pagename, the page generated for the above chapter would beoutput_directory/intro.html.After setting pagenameto "introduction", the page generated for the above chapter isoutput_directory/introduction.html.
- samepage
- Specifies that the book division (e.g. a section) is to be generated
      in the same output HTML file as its parent book division (e.g. a
      chapter). By default, all book divisions are generated by
      ebookc in their own HTML files. Example:1 2 3 4 <chapter href="ch1.html"> <section href="ch1/s1.html" samepage="true"/> <section href="ch1/s2.html"/> </chapter> Attribute samepage="true"instructs ebookc to generate the content of the chapter and the content of the first section in the same HTML file. The second section having an impliedsamepage="false"is created in its own HTML file.Note that something like: 1 2 3 4 <chapter href="ch1.html"> <section href="ch1/s1.html"/> <section href="ch1/s2.html" samepage="true"/> </chapter> is an error because there is no way for ebookc to generate two sibling sections in the same output HTML file. 
- xml:base
- Specifies a base URL which used to resolve the relative URLs found in the ebook specification.
- xml:lang
- Ignored for any element other than book, for which it specifies the main language of the book.
- xml:id
- Specifies the unique ID of an element of the ebook specification.
      Specifying an xml:idattribute is useful in the following cases:- It is required for a book division to be referenced in a relatedelement. Example:1 2 3 <chapter href="ch1.html" xml:id="ch01"> <related ids="ch01 ch02 ch03" xml:id="rel1"/> </chapter> 
- It allows the inclusion of ebook elements using XInclude. In the preceding example,
          relatedelement "rel1" is defined in first chapter. In the following example, a copy ofrelatedelement "rel1" is included in the second chapter:1 2 3 4 <chapter href="ch2.html" xml:id="ch02"> <xi:include href="" xpointer="rel1" set-xml-id="" xmlns:xi="http://www.w3.org/2001/XInclude"/> </chapter> 
- It may be used to control the IDs generated in the output HTML
          pages. Example:1 2 3 <chapter href="ch3.html" xml:id="going_further"> <section href="ch3/s1.html" xml:id="requirements" samepage="true"/> </chapter> - The htmlelement of the output page containing the chapter will haveid="going_further". All the elements “pulled” from "ch3.html" will have their IDs prefixed with "going_further__".
- The sectionelement containing the section will haveid="requirements". All the elements “pulled” from "ch3/s1.html" will have their IDs prefixed with "requirements__".
 
- The 
- Referencing the value of an xml:idattribute in proprietary attributedata-xml-id-refmay be used to create links to locations that do not exist in the input HTML pages, but which will be created in the output HTML pages. Example:1 2 3 4 5 <chapter xml:id="ch04"> <head><title>...</title></head> <section href="ch4/s1.html"/> <section href="ch4/s2.html"/> </chapter> In input HTML page " ch4/s2.html", you may refer to the first section of the chapter by writing<a href="s1.html"/>. But how to refer to the chapter itself? Notice that this chapter has no input HTML page to refer to.The solution to this problem is to add proprietary attribute data-xml-id-refto anaelement. For the above example, it's<a data-xml-id-ref="ch04"/>.Note that writing <a href="s1.html" data-xml-id-ref="ch04"/>is an even better option becausehref="s1.html"is used as a fallback link target in casexml:id="ch04"is not defined in the ebook specification.
 
- It is required for a book division to be referenced in a 
- Any XHTML5 global attribute, including any attribute
      having a name starting with "data-"
- These attributes (e.g. class,dir,lang,onclick,style) are copied to the output HTML element corresponding to the book division. Example: the output HTML element corresponding to the following appendix:<appendix href="a2.html" samepage="true" class="disclaimer" lang="fr-FR"/> is: <html:section class="role-appendix disclaimer" lang="fr-FR"/> Specifying an idattribute for a book division is likely to cause broken links in the output HTML files.