Discussion Groups / English Usage / January 2007

Hm, they speak about two **parallel** hyphens here:
http://en.wikipedia.org/wiki/Double_hyphen

Marius Hancu

As far as I can tell, the MWCD11 has no such entry in the "A Handbook of
Style" section.  The only division-of-words-at-end-of-line mention is of
a simple hyphen: 'hyphen', 10. p. 1607. Nor do I find it in the
"Explanatory Notes", but even if it *is* there, it hardly matters for
English usage: that section is to explain the *non-standard* uses to
which the dictionary puts various marks.

MWCD10 and MWCD11 also use the double hyphen symbol when it is
typographically necessary to split a word at an existing hyphen.
They have to do so because people use the dictionary as a
hyphenation authority; the symbol is not used in ordinary contexts.

I became more familiar with MWCD10 than I might have liked, when I
edited an official North American list of words acceptable in Scrabble.
I found the double hyphenation convention very helpful at the time, as
without it I could not have determined whether the required presence of
a hyphen in a compound word rendered the word unacceptable for use in
Scrabble.

John