Sometimes URIs will need to include some parts that are based on more or less free-form user input, and in those cases the possibility exists that users will enter special characters which either are not allowed in URIs at all, or may cause problems with the automated parsing of your URIs. In those cases, instead of restricting what users can enter (except when it makes sense, for instance for a slot or port number), it is preferable to escape or encode the user-entered string. Our preferred mechanism to achieve this is to URL-encode those parts using a UTF-8 encoding.