How to set undefinedRAtom option for an undefined R-atoms

Hi. I would like to know if there is a way to set undefinedRAtom option for an undefined R-atoms when using the reactor GUI.Thank you very much for your answer in advance.

No, this option cannot be set from the Reactor GUI. Could you share with us why do you want to modify it? 

It is possible to modify the undefinedRAtom option via the Java/.NET API. The default value is UNDEF_R_MATCHING_GROUP.

Thanks for the answer. It was pure curiosity.