Headed group of material; the basic structural unit of the body of a document.
A very short book or chapter may contain nothing but paragraphs (and other paragraph-level elements such as figures and tables), but most books and book components are divided into either titled book parts (<book-part>) or titled sections (<sec>).
A section must have some sort of title, so that, for example, a Table of Contents can be automatically generated. Therefore, this Tag Set requires that a section be tagged with (minimally) either a <title> or a <label>. A section may be tagged with both.
Sections are recursive, that is, various levels of sections are indicated by containment, not by different names for the subsections. A <sec> element may contain lower level sections that are also tagged using the <sec> element, not tagged explicitly as <sec2>, <sec3>, or <subsec1>, etc.
<!ELEMENT sec %sec-model; >
((object-id)*, sec-meta?, label?, title?, subtitle*, alt-title*, (address | alternatives | answer | answer-set | array | boxed-text | chem-struct-wrap | code | fig | fig-group | graphic | media | preformat | question | question-wrap | supplementary-material | table-wrap | table-wrap-group | disp-formula | disp-formula-group | def-list | list | tex-math | mml:math | p | related-article | related-object | ack | disp-quote | speech | statement | verse-group | x)*, (sec)*, (notes | fn-group | glossary | ref-list | sig-block)*)
The following, in order:
<abstract>, <ack>, <answer>, <app>, <back>, <bio>, <body>, <boxed-text>, <named-book-part-body>, <notes>, <question>, <sec>, <trans-abstract>
<book dtd-version="1.0">
...
<front-matter>...</front-matter>
<book-body>
<book-part id="bid.1" book-part-type="part">
<book-part-meta>...</book-part-meta>
<body>
<book-part id="bid.2" book-part-type="chapter">
<book-part-meta>
<title-group>
<label>1</label>
<title>GenBank: The Nucleotide Sequence Database</title>
</title-group>
...
<abstract>
<title>Summary</title>
<p>The GenBank sequence database is an annotated collection ...</p>
...
</abstract>
</book-part-meta>
<body>
<sec id="bid.3">
<title>History</title>
<p>Initially, GenBank was built and maintained at Los Alamos National
Laboratory ...</p>
</sec>
...
</body>
...
</book-part>
...
</body>
</book-part>
...
</book-body>
...
</book>