%% You should probably cite rfc7986 instead of this I-D.
@techreport{ietf-calext-extensions-00,
    number =    {draft-ietf-calext-extensions-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-ietf-calext-extensions/00/},
    author =    {Cyrus Daboo},
    title =     {{New Properties for iCalendar}},
    pagetotal = 21,
    year =      2015,
    month =     apr,
    day =       6,
    abstract =  {This document defines a set of new properties for iCalendar data as well as extending the use of some existing properties to the entire iCalendar object.},
}