RMS 4.6 The site or server is undergoing maintenance
HTTP status: 503 Service unavailable
HTTP headers: Retry-After (optional)
Either a timestamp (HTTP-date) or an integer number of seconds signifying when it is expected the resource will be available again.
Content element to contain the following text:
The requested resource is currently unavailable due to server maintenance
An optional custom message can be included here.
Services are expected to be restored at a later date*.
Please contact us if you require further assistance with your request.
*Optionally this text can be replaced with a specific date and/or time (specifying AEST) that it is expected the resource will become available again (in which case a Retry-After header should also be used).