Web Design in a Nutshell, 3rd Edition

XML Declaration

The first line of the example is the XML declaration.

<?xml version="1.0" encoding="US-ASCII" standalone="no"?>

The XML declaration contains special information for the XML parser. First, the version attribute tells the parser that it is an XML document that conforms to Version 1.0 of the XML standard (which, incidentally, is the only available option).

In addition, the encoding attribute specifies which character encoding the document uses. By default, XML use the UTF-8 encoding of the Unicode character set (the most complete character set including glyphs from most of the world’s languages). Alternate encodings may also be specified, such as ISO-8859-1 (Latin-1), which is a set containing characters from most Western European languages. Character encodings are discussed in more detail in Chapter 6.

Finally, the optional standalone="no" attribute informs the program that an outside DTD is needed to correctly interpret the document. If the value of standalone is yes, it means there is no DTD or the DTD is included in the document.

XML documents should begin with an XML declaration, but it is not required.

Warning

In XHTML documents, the presence of an XML declaration will cause Internet Explorer 6 for Windows to render in Quirks mode, even when a proper DOCTYPE declaration is provided (see Chapter 9 for information on Quirks versus Standards mode and DOCTYPE switching). For this reason, it is commonly omitted. This problem has been fixed in IE 7. Some other browsers may ...