%% You should probably cite rfc8710 instead of this I-D.
@techreport{ietf-core-multipart-ct-04,
    number =    {draft-ietf-core-multipart-ct-04},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-ietf-core-multipart-ct/04/},
    author =    {Thomas Fossati and Klaus Hartke and Carsten Bormann},
    title =     {{Multipart Content-Format for the Constrained Application Protocol (CoAP)}},
    pagetotal = 9,
    year =      2019,
    month =     aug,
    day =       21,
    abstract =  {This memo defines application/multipart-core, an application-independent media type that can be used to combine representations of zero or more different media types (each with a Constrained Application Protocol (CoAP) Content-Format identifier) into a single representation, with minimal framing overhead.},
}