No. The iron-rubber mat is covered with a thin pvc layer on which the graphic is printed with the ultraviolet method. The print is very resistant but you cannot write on it, thinking about canceling later.
You can do it, but if you want to keep some of the magnetic strength of the system you have to use a mat whose thickness does not exceed half a millimeter. Otherwise the cards would still stand up only with the supports, but you would no longer have the magnetizing effect.