Form calculation with manual input

Actually when I'm in the calculation field, I can choose what to insert ONLY by selecting one by one the single questions I'm evaluating. Since the input menu is messy, It will be super useful to manually add their own field name (in this case I'm using a code) for the calc. I have this example: I need to add only the items that have a certain code, hidden to the client. If I have to select individually the questions, it'd be a huge waste of time. If instead, THE INPUT MENU IS ENABLED, I can just add all the items I've given a code to, like this:

{RESIL01}+{RESIL02}+{RESIL03}+{RESIL04}+{RESIL05}+ .....

without picking one by one the questions.

Basically, it's just making directly editable the input menu in which these code appear. Let us just input them manually without rematching question and code.

I hope I did make myself clear, if not, just ask.

For me this is a matter of the uttermost importance.

Thank you, waiting for your reply.

Fabri