Hi everyone, With the command \definemathfence it is possible to define for instance the following command \definemathfence[duality][angle][command=yes,factor=auto] so that $\duality{T,\phi}$ results in $\langle T,\phi \rangle$ and the \langle and \rangle are appropriately scaled when necessary. How can one create a command called \bracparenth in order to get a left bracket on the left and a right parenthesis on the right, that is $\bracparenth{a,b} = [a,b)$ and so that when necessary it scales automatically. Below is the example for \duality. Thanks in advance: OK %%% begin mathfence-example.tex \definemathfence[duality][angle][command=yes,factor=auto] \definemathfence[parenth][parenthesis][command=yes,factor=auto] \starttext The action of $T$ on a smooth function $\phi$ is denoted by \startformula \duality{T,\phi} \stopformula while the scalar product of two functions $f$ and $g$ is denoted $\parenth{f|g}$. \stoptext %%% end mathfence-example.tex