N/A Checkbox will allow website builders to add a checkbox next to a number textfield. The idea is to provide the users a textfield to enter a numeric value, or mark N/A in case they don't have it. When the N/A option is marked, a different value is set in the database so that it knows what was selected.
Both the internal value of the checkbox and the N/A label are configurable. The internal value can be outside of the max, min, and allowed values and it will still validate properly.
To use this module, go into the CCK field editing form in Administer >> Content management >> Content types >> Manage fields and select the field you want to enable N/A Checkbox for.
You can now configure the value that will be stored and the label that will be displayed.