Bob Braden wrote:
in a book seems to be tacityly admitting that the book will be
worthless after 6 months. Which, one suspects, is probably true
for most books that reference Internet Drafts.
Cute, but wrong.
Books highlight (a) the contents of an I-D, and/or (b) the fact
that an I-D ever existed on a topic. It is immaterial whether
the IETF decides, in its wisdom, to progress (or not) a
particular I-D. The book's author makes his/her own decision
whether to acknowledge the (possibly historical) existence of
a document, written by certain people named in the cite, that is
(or was) associated with the topic is being discussed at the
point in the book where the cite is introduced. If the I-D has
since expired, the cite still serves as a beacon identifying
a historical event and the people involved. Sometimes this is
even considered polite.