1.3.4.2 http://schemas.microsoft.com/mapi/id Namespace

The http://schemas.microsoft.com/mapi/id namespace is used to access named properties on the server that are identified by a property long ID (LID). The implementer can access these properties through WebDAV by appending the property set and the hexadecimal property long ID (LID) value to the namespace prefix.

 id-specifier = "http://schemas.microsoft.com/mapi/id/" property-set "/x" property-long-id
  
 property-set = "{" 8HEXDIG "-" 4HEXDIG "-" 4HEXDIG "-" 4HEXDIG "-" 12HEXDIG "}"
  
 property-long-id = 8HEXDIG

Example:

 http://schemas.microsoft.com/mapi/id/{00062002-0000-0000-C000-000000000046}/x00008213 (PidLidAppointmentDuration)