%% You should probably cite rfc8607 instead of this I-D.
@techreport{ietf-calext-caldav-attachments-03,
    number =    {draft-ietf-calext-caldav-attachments-03},
    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/03/},
    author =    {Cyrus Daboo and Arnaud Quillaud and Kenneth Murchison},
    title =     {{CalDAV Managed Attachments}},
    pagetotal = 36,
    year =      2017,
    month =     jul,
    day =       24,
    abstract =  {This specification defines an extension to the calendar access protocol (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 non-standard method of updating an existing resource via HTTP.},
}