This field can be entered in an action of the type "Miscellaneous process". There is no supervisor process associated with this action, only with this sub-program. It is defined either in the standard process, or in the specific/custom process.
A single sub-program is executed : This is the specific/custom if the process exists, if not it is the standard. The addition of a customization to a standard action of the type "Miscellaneous process" is then cancelled and replaced.