It is available only since the patch 1.2.
Publish a state, then with small Fichier/Liste of the variables...,
this window appears:
You can notice the appearance of the button [... ] (active only if one
is in the case of an expression. Cliquez to launch the editor above:
One can notice a small air of resemblance not?
If you cliquez on the button [ Ajouter ] zone " functions " or on the
button [(< X >)] you will déclancherez the editor of parameters
According to the number of parameters, you will have zones of edition more
The button [... ] makes it possible to launch the generator of expressions
to inform the parameter.
In short, there is not great a deal to say above