4.2 Extension Functions

MonetDB/XQuery offers various non-W3c recommended builtin functions, organized in the following categories:

• Document Management Functions: adding and deleting documents.
• Metadata Functions: query what document collections are stored (the catalog).
• NID Functions: obtaining and using persistent node-identifiers (NIDs).
• Arithmetic Functions: math functions that are missing in the XQuery spec.
• PF/Tijah Functions: functions for keyword search and ranking.
• Probabilistic XML: edit-distance, deep-equal