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Radicale-Custom-DAV-protocol-extensions.md

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+## Radicale DAV Extensions
+Radicale uses standard DAV protocol extensions as defined in RFC 4918, however, some custom extensions are used to enhance the functionality of the Radicale Web UI client. These custom protocols are not used by the Radicale server when processing CalDAV and CarDAV requests and do not need to be supported by any clients.
+
+### displayname
+The ```displayname``` extension is used to retrieve the display name of a collection if it has been set. It returns a string containing the name or an empty value if none is set. This extension is similar to the standard DAV extension of the same name except it will return an empty value if there is no display name set, whereas the standard DAV extension will return the collection URL if there is no display name set.
+
+### getcontentcount
+The ```getcontentcount``` extension is used to retrieve the number of individual items within a collection. It can only be used for collections. It returns an integer of the total number of items stores or a 0 if there was an error.
+
+## XML Namespace
+The XML namespace of the Radicale custom DAV extensions is ```http://radicale.org/ns/``` and the XML prefix is ```RADICALE```. An example of using the Radicale namespace in a DAV request would look like this:
+```
+<?xml version="1.0" encoding="utf-8" ?>
+<propfind xmlns="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav" xmlns:CR="urn:ietf:params:xml:ns:carddav" xmlns:CS="http://calendarserver.org/ns/" xmlns:I="http://apple.com/ns/ical/"xmlns:INF="http://inf-it.com/ns/ab/" xmlns:RADICALE="http://radicale.org/ns/">
+	<prop>
+		<resourcetype />
+		<RADICALE:displayname />
+		<I:calendar-color />
+		<INF:addressbook-color />
+		<C:calendar-description />
+		<C:supported-calendar-component-set />
+		<CR:addressbook-description />
+		<CS:source />
+		<RADICALE:getcontentcount />
+		<getcontentlength />
+	</prop>
+</propfind>
+```