%% You should probably cite rfc8674 instead of this I-D.
@techreport{nottingham-safe-hint-00,
    number =    {draft-nottingham-safe-hint-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-safe-hint/00/},
    author =    {Mark Nottingham},
    title =     {{The "safe" HTTP Client Hint}},
    pagetotal = 6,
    year =      2013,
    month =     oct,
    day =       21,
    abstract =  {This specification defines a "safe" HTTP Client Hint, expressing a user preference to avoid "objectionable" content.},
}