Editing Courses/EPUB/day1 (section)

== content document .xhtml ==
Content documents are '''the place-holders for text and images in an ePub'''.

In EPUB 3, content documents are XHTML5(HTML5 + XML), under '''.xhtml''' file extension.

What you find in a ePub content document is essentially what you find behind webpage: HTML code.

EPUB3 allows the use of '''HTML5''', including elements such as <code><section>, <article>, <nav>, <header>, <footer>, <aside>.
<video>, <audio></code> and Mathematical Markup Language (MathML). However keep in mind that some of these tags wont work with much of the current ereaders, which are only prepared to render EPUB 2 ePubs.


As a rule of thumb is good to have '''chunk content into several documents''', either one for each section or subsection of a book.
The reason for this, is that ereaders are often slow and take their time to render the content. To facilitate their job is a good practice to have the content divided in smaller pieces. 

=== XML requirements ===
As content document are HTML with added XML they obey the stricter XML rules:
* every element has an opening and closing tag.
* Empty tags such as <br> must be self-closing: '''<br/>'''
* Elements and attribute names are case-sensitive and always lowercase.
* Namespaces must be declared (for embedded MathML, SVG, EPUB elements and attributes, etc.).
* Ampersands (&) must be escaped as &amp;.

Example of a content document:
<source lang="xml">
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops">
  <head>
    <meta charset="utf-8" />
    <meta content="pandoc" name="generator" />
    <title>Acknowledgments</title>
    <link href="stylesheet.css" rel="stylesheet" type="text/css" />
  </head>
  <body>
    <section class="level1" epub:type="acknowledgments frontmatter" id="acknowledgments">
      <h1>Acknowledgments</h1>
      <p>In fall 2012, as part of my graduate studies, I began studying Instagram user self-portraits. The users whose images I discuss in this notebook may or may not have knowledge that I critiqued their selfies, as I did not interview users about their images. My study is assumptive, and my work is influenced by the research of Marshall McLuhan and Vilém Flusser. Thank you to the users who kindly gave me permission to republish their images.</p>
    </section>
  </body>
</html>
</source>  



=== semantic inflection ===
It is possible to enrich the content documents with [http://www.idpf.org/epub/30/spec/epub30-contentdocs.html#sec-xhtml-semantic-inflection '''semantic inflection''']. In other words, to attach meaning about the purpose or nature an element to itself. 

Semantic inflections use the <code>epub:type</code> attribute to describe the content contained within that element. The terms that can be used in these inflections can be found at http://www.idpf.org/epub/vocab/structure/

In the previous example epub:type appears in <code><section class="level1" epub:type="acknowledgments frontmatter" id="acknowledgments"></code>. It informs us, and the reading system that the current section belongs to the book's frontmatter and constitutes the acknowledgments.