\cdbproperty{Coordinate}{}

Declare a symbol to be a coordinate label (useful in combination
  with \subsprop{Depends}). This is required if you want to write a
  derivative with respect to a coordinate: the input
\begin{screen}{1}
A(x,x') + \diff{B(x,x')}_{x};
\end{screen}
will by default be seen as incorrect because the $x$ in the second
term will be considered an index label, not a coordinate. The input
\begin{screen}{1,2}
{ x, x' }::Coordinate.
A(x,x') + \diff{B(x,x')}_{x};
\end{screen}
is allowed and interpreted in the right way.

\cdbseeprop{Symbol}
