%% You should probably cite draft-hellstrom-slim-modality-grouping instead of this I-D.
@techreport{hellstrom-language-grouping-00,
    number =    {draft-hellstrom-language-grouping-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-hellstrom-language-grouping/00/},
    author =    {Gunnar Hellstrom},
    title =     {{Human Language Modality Grouping Semantics in Session Description Protocol}},
    pagetotal = 10,
    year =      2017,
    month =     jun,
    day =       11,
    abstract =  {In a real-time communication session, there may be a need or preference for receiving the same content in two or more simultaneous modalities. There may also be a need to prioritize which media to use for language communications. This document defines the semantics for grouping media in the Session Description Protocol (SDP) containing human languages in order to assign their relative priority and also grouping media that are desired to be received together. The semantics defined in this document are to be used with the SDP Grouping Framework. Applications are for example a possibility to indicate when a sign language is most desired, but written language an acceptable lower rated alternative, offered for the other party to select between. Applications are also for indication of need for both spoken and written content in a real-time call (captioning) together, or provision of both spoken language original and sign language interpretation of the original language together in a real- time session. These indications are specified for the sending and receiving direction separately.},
}