%% You should probably cite draft-ietf-calext-extensions instead of this I-D.
@techreport{daboo-icalendar-extensions-05,
    number =    {draft-daboo-icalendar-extensions-05},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-daboo-icalendar-extensions/05/},
    author =    {Cyrus Daboo},
    title =     {{New Properties for iCalendar}},
    pagetotal = 23,
    year =      2012,
    month =     jun,
    day =       10,
    abstract =  {This document defines a set of new properties for iCalendar data.},
}