Seems to me they used to cause problems and in fact terminated the
parameter and begun a comment.  Thus, in
 
     REPLY-TO=LIST, RESPECT
 
the word RESPECT was treated as a comment.  Am I imagining this?  The
reason I ask is the "A description of list header keywords" being
prepared has an example of
 
     SUBSCRIBE=OPEN, CONFIRM
 
which I believe is incorrect because of the space.