%% You should probably cite rfc4917 instead of this I-D.
@techreport{ietf-mip4-message-string-ext-03,
    number =    {draft-ietf-mip4-message-string-ext-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-mip4-message-string-ext/03/},
    author =    {Venkateshwara Sastry and Alpesh Patel and Kent Leung},
    title =     {{Mobile IPv4 Message String Extension}},
    pagetotal = 7,
    year =      2007,
    month =     mar,
    day =       2,
    abstract =  {This document specifies a new extension for use in Mobile IPv4. This extension can be added by the Home Agent and the Foreign Agent to Registration Reply messages. This extension carries a text string that is intended for the user of the Mobile Node. {[}STANDARDS-TRACK{]}},
}