Catharine Roth (added note) on 29 August 2002@01:51:18. Catharine Roth (added cross-reference) on 29 August 2002@01:52:52. David Whitehead (augmented note; cosmetics) on 21 January 2007@09:48:00. David Whitehead (more keywords; tweaking) on 9 May 2012@05:18:42. David Whitehead on 11 September 2015@08:05:34.