1.3.4.3 http://schemas.microsoft.com/mapi/string Namespace

The http://schemas.microsoft.com/mapi/string namespace is used to access named properties on the server that are identified by a property name. The implementer can access these properties through WebDAV by appending the property set and the property name to the namespace prefix.

 string-specifier = "http://schemas.microsoft.com/mapi/string/" property-set "/" property-name
  
 property-set = "{" 8*HEXDIG "-" 4*HEXDIG "-" 4*HEXDIG "-" 4*HEXDIG "-" 12*HEXDIG "}"
  
 property-name = 1*CHAR

Example:

 http://schemas.microsoft.com/mapi/string/{00020329-0000-0000-C000-000000000046}/Subject (PidNameSubject)