%% You should probably cite draft-ietf-sipcore-multiple-reasons instead of this I-D.
@techreport{sparks-sipcore-multiple-reasons-00,
    number =    {draft-sparks-sipcore-multiple-reasons-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-sparks-sipcore-multiple-reasons/00/},
    author =    {Robert Sparks},
    title =     {{Multiple SIP Reason Header Field Values}},
    pagetotal = 4,
    year =      2021,
    month =     nov,
    day =       12,
    abstract =  {The SIP Reason Header Field as defined in RFC 3326 allows only one Reason value per protocol value. Practice shows it is useful to allow multiple values with the same protocol value. This update to RFC 3326 allows multiple values for an indicated registered protocol when that protocol defines what the presence of multiple values means.},
}