XML declaration

One thing I forgot about a well-formed document, is that it should have an XML declaration.

• An XML declaration is not mandatory
• It have 3 attributes that have a specific order
• version - Must always be included, currently the only possible value is "1.0"
  
• encoding - Specifies the character set use in the document, defaults to "UTF-8"
  
• standalone - Specifies if the document relys on extanal documents, such as a DTD or XML schema. Defaults to "no"
  
• Must start at the first character of the XML document

Example of XML declaration
<?xml version="1.0" encoding="iso-8859-1" standalone="no"?>