Special Value for Numeric Question


What is the callback function used for the special value in a Numeric question?

i want to create an enabling condition that will be hinged on the special value, not on the actual numeric answer.

Thanks for the help in advance!

there are no any callback functions in Survey Solutions, at least in the sense it is traditionally understood:

A special value is just a numeric value. When it is selected the value of the numeric question is that value (and it is considered answered). For example,

How much land do you own? _________
0=Respondent doesn’t own any land.

Best, Sergiy