HTML & XHTML: The Definitive Guide, 6th Edition

Text Conventions

Throughout the book, we use a constant-width typeface to highlight any literal element of the HTML/XHTML standards, tags, and attributes. We always use lowercase letters for tags.^[*] We use italic for filenames and to indicate new concepts when they are defined. Elements you need to supply when creating your own documents, such as tag attributes and user-defined strings, appear in constant-width italic in the code.

We discuss elements of the language throughout the book, but you'll find each one covered in depth (some might say in nauseating detail) in a shorthand, quick-reference definition box that looks like the one that follows (for the <title> element). The first line of the box contains the element name, followed by a brief description of its function. Next, we list the various attributes, if any, of the element: those things that you may or must specify as part of the element.

<title>

Function	Defines the document title
Attribute	dirlang
End tag	</title>; never omitted
Contains	plain_text
Used in	head_content

The icon ‼ identifies tags and attributes that aren't in the HTML 4.01 or XHTML 1.0 standards, and those that are handled very differently between the various popular browsers.

The description also includes the HTML ending tag, if any, for the element, along with a general indication of whether the end tag may be safely omitted in general use in HTML. For the few tags that require end tags in XHTML, but do not have them in HTML, the language lets ...