Thanks for the input everyone. I've settled (for now) on the following:
<abbr title="B flat">Bb</abbr>
My magic conversion to pander to IE's non-support of <abbr> [1] has now
been turned off as it made any music-related pages a mass of conditional
comments. People who want abbreviations expanded can either get a
browser or view the source.
I understand that e.g. Bb isn't really an abbreviation, but I think it's
probably the closest semantically. Perhaps <code> would have been
appropriate?
Now all I need to do is update the crazy number of occurrences.
[1] It converted <abbr title="foo">bar</abbr> to:
<abbr title="foo"><!--[if IE]<acronym title="(fixed abbr for IE)
foo">bar</acronym><![endif]--></abbr>
--
Mark.
http://tranchant.plus.com/