> > By this do you mean the rabbet joint?
> > See http://www.azwoodman.com/boxes/butt-joint.jpg
> > for a picture.
>
> The caption of the diagram says that's a butt joint,

Actually the caption says "rabbet-butt"

> and it looks like a butt joint to me.

One end is clearly labelled "butt cut" the other end is marked "rabbet cut".
A butt joint is made with two butt cut pieces.

> A "rabbet" is any grove in board.

Interesting syntax.  Assuming you meant "any groove in (a) board), I think
the word you need here is "dado".
http://education.yahoo.com/reference/dictionary/entries/43/d0004300.html .

A rabbet is specifically at the end, and usually made for joining, although
other uses are sometimes made -- as in beekeeping frame rests.

VARIANT FORMS: also re·bate ( rbt,  rbt)
NOUN: 1. A cut or groove along or near the edge of a piece of wood that
allows another piece to fit into it to form a joint.
2. A joint so made.
VERB: Inflected forms: rab·bet·ed also re·bat·ed, rab·bet·ing, re·bat·ing,
rab·bets, re·bates

See http://education.yahoo.com/reference/dictionary/entries/14/r0001400.html
for a further illustration, similar to the one at
http://www.azwoodman.com/boxes/butt-joint.jpg

> A common example
> is the grove cut in the top of a super upon which the
> frames rest (confusingly called a "rebate" by some).

> > due to the softwood lumber dispute.
>
> Dispute?  There's no dispute.
<uninformed garbage deleted>

I am disappointed in you Jim. That was a deliberate, off-topic troll.   It
was also spectacularly uninformed.

'Softwood lumber dispute' is the term that is used on *both* sides of the
border to describe whatever has caused the idling of Canadian mills and
widespread availability of good lumber for Canadian beekeepers.  (And higher
prices for US beekeepers, I might add)

Check out the joinery references above, then after you learn something about
carpentry, why not learn something about the dispute?  Just do a quick
Google search on 'softwood lumber dispute'.  You'll find sources on both
sides of the border using the term, and you will also know what you are
talking about next time.

allen