W3C home > Mailing lists > Public > w3c-sgml-wg@w3.org > March 1997

Re: those predeclared entity refs

From: <John_Lavagnino@Brown.edu>
Date: Fri, 14 Mar 1997 23:31:11 -0500 (EST)
Message-Id: <199703150431.XAA11333@ursula.stg.brown.edu>
To: w3c-sgml-wg@w3.org
Peter Murray-Rust:

|   > At 6:37 PM 3/13/97, lee@sq.com wrote:


|   > >That makeds five; do we also need
|   > >gt      right angle brcket        >
|   > >or
|   > >ket     right bracket             ]
|   I have a nasty feeling that physicists use 'bra' for '<' and 'ket' for '>'
|   and I suspect this could cause serious confusion in at least part of
|   the community.

Back when my field was physics and not literature, "bra" and "ket" did
not refer to bare < and > but to larger entities like <a| and |b>.
The short explanation is that these are vectors.  The vertical bar was
essential, and generally the letter too so that you knew what variable
you were talking about; < and > on their own would not be
distinguishable from less-than and greater-than signs.  So I don't
think using "bra" and "ket" to refer to other single symbols would be
an enormous problem, because for physicists they don't meaningfully
refer to single characters anyway.  (I also had the impression that
this notation is no longer much used, but that could be subject to a
lot of local variation.)

The second edition of the OED will give you a reasonable picture of
the origin and use of this notation.

John Lavagnino
Received on Friday, 14 March 1997 23:31:05 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 21:25:23 UTC