The XML 1.0 specification allows content to follow the end tag of the document element. However, permitted content is restricted to only comments, processing instructions, and whitespace. In practice, this means that all document content must be nested within the document element. Markup after the end tag of the document element can contain only information intended for a human reader, given in comments, or one or more processing instructions for the XML processor or the application. No constraint affects the ordering of comments or processing instructions.