\cdbproperty{CommutingAsSum}{}

This makes an object behave, for purposes of commutation rules, as a
sum.
\begin{screen}{1,2,3}
A(#)::CommutingAsSum.
{Q,X,Y,Z}::AntiCommuting.
A(Y)(Z)*A(X);
@prodsort!(%);
(-1) A(X) A(Y)(Z);
\end{screen}
The minus sign arises because it would also have been present when
sorting the expression {\tt (Y+Z)*X}. 

Note that this does not (yet) work when the arguments are given as a
list separated by commas, as in {\tt A(Y,Z)}.

\cdbseeprop{CommutingAsProduct}
\cdbseeprop{AntiCommuting}

