%% You should probably cite draft-ietf-httpbis-retrofit instead of this I-D.
@techreport{nottingham-http-structure-retrofit-00,
    number =    {draft-nottingham-http-structure-retrofit-00},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-nottingham-http-structure-retrofit/00/},
    author =    {Mark Nottingham},
    title =     {{Retrofit Structured Fields for HTTP}},
    pagetotal = 14,
    year =      ,
    month =     ,
    day =       ,
    abstract =  {This specification defines how a selection of existing HTTP fields can be handled as Structured Fields.},
}