Dear Hans and others,

I'm usually use the \big, \Big, \bigg etc to get the size of parentheses,
brackets and braces to be the size I want. I realize that the fences
machinery is probably a cleaner way of doing this.

I tried it a bit, and it usually gives the result I like. But sometimes
not, and it seems that the way to change the size of the
parentheses/brackets/braces is to use the factor key.

1) Are the different options none, auto NUMBER explained somehere?
2) Could one have, for exceptional cases where the default is not
satisfactory, a keyword like factor=big for example, to get the same size
as if one would have used \big?

I am a bit confused. See the example below, with output (from latest
standalone) attached.

/Mikael

PS: I would suggest to have
 italic       = { feature = 'ss01', value = 1, comment = "Mathematical
Alternative Lowercase Italic" },
set in lucida-opentype-math.lfg. In all books (on math) I have seen, I
think this is what is used.

%%% Example file:

\setupbodyfont[lucidaot]

\definemathfence[Set][left="007B,right="007D,command=yes]

\startbuffer
\startformula
\Set{x\in\mathbb R~:~x^2=1}
\stopformula
\stopbuffer


\startTEXpage[offset=3bp]

\startformula
\{x\in\mathbb R~:~ x^2=1\}%Too small
\stopformula

\startformula
\bigl\{x\in\mathbb R~:~ x^2=1\bigr\}%I like this one
\stopformula

\startformula
\Bigl\{x\in\mathbb R~:~ x^2=1\Bigr\}%Too big
\stopformula

\getbuffer

\setupmathfence[Set][factor=1]%I like this one
\getbuffer

\setupmathfence[Set][factor=auto]%Too big
\getbuffer

%\setupmathfence[Set][factor=big]%Perhaps this could work? Or size=big or
something
%\getbuffer
\stopTEXpage