The MCU software may provide strings to the XML-RPC API of up to 31 characters long, unless otherwise stated in the documentation. In some cases, the API will accept longer strings and truncate the stored / returned values to 31 characters. In others, the API will return a fault code if the value is unexpected or not allowed.
The name parameter, for example, in the participant.add call, is limited to 31 characters. This is true despite the fact that the API documentation does not explicitly list the parameter length.