Most XML documents start with an XML declaration that provides basic information about the document to the parser. An XML declaration is recommended, but not required. If there is one, it must be the first thing in the document.
The declaration can contain up to three name-value pairs (many people call them attributes, although technically they're not). The version is the version of XML used; currently this value must be 1.0. The encoding is the character set used in this document. The ISO-8859-1 character set referenced in this declaration includes all of the characters used by most Western European languages. If no encoding is specified, the XML parser assumes that the characters are in the UTF-8 set, a Unicode standard that supports virtually every character and ideograph from the world's languages.
Finally, standalone, which can be either yes or no, defines whether this document can be processed without reading any other files. For example, if the XML document doesn't reference any other files, you would specify standalone="yes". If the XML document references other files that describe what the document can contain (more about those files in a minute), you could specify standalone="no". Because standalone="no" is the default, you rarely see standalone in XML declarations.
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发表于 2015-10-5 12:35:30
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