%% You should probably cite rfc9253 instead of this I-D.
@techreport{ietf-calext-ical-relations-01,
    number =    {draft-ietf-calext-ical-relations-01},
    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-calext-ical-relations/01/},
    author =    {Michael Douglass},
    title =     {{Support for iCalendar Relationships}},
    pagetotal = 19,
    year =      2017,
    month =     feb,
    day =       3,
    abstract =  {This specification updates RELATED-TO and introduces new iCalendar properties LINK, STRUCTURED-CATEGORY and REFID to allow better linking and grouping of iCalendar components and related data.},
}