%% You should probably cite rfc8607 instead of this I-D.
@techreport{ietf-calext-caldav-attachments-04,
    number =    {draft-ietf-calext-caldav-attachments-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-calext-caldav-attachments/04/},
    author =    {Cyrus Daboo and Arnaud Quillaud and Kenneth Murchison},
    title =     {{Calendaring Extensions to WebDAV (CalDAV): Managed Attachments}},
    pagetotal = 34,
    year =      2019,
    month =     mar,
    day =       5,
    abstract =  {This specification adds an extension to the Calendaring Extensions to WebDAV (CalDAV) to allow attachments associated with iCalendar data to be stored and managed on the server. This specification documents existing code deployed by multiple vendors. It is published as an Informational specification rather than Standards Track due to its noncompliance with multiple best current practices of HTTP.},
}