@misc{rfc7444,
    series =    {Request for Comments},
    number =    7444,
    howpublished =  {RFC 7444},
    publisher = {RFC Editor},
    doi =       {10.17487/RFC7444},
    url =       {https://www.rfc-editor.org/info/rfc7444},
    author =    {Kurt Zeilenga and Alexey Melnikov},
    title =     {{Security Labels in Internet Email}},
    pagetotal = 16,
    year =      2015,
    month =     feb,
    abstract =  {This document describes a header field, SIO-Label, for use in Internet email to convey the sensitivity of the message. This header field may carry a textual representation (a display marking) and/or a structural representation (a security label) of the sensitivity of the message. This document also describes a header field, SIO-Label-History, for recording changes in the message's label.},
}