The plug-in has built-in validation which is executed when the interactive grid is saved.
If the value of a column using the plug-in is equal the Value When Checked or Value When Not Checked attribute or is NULL then validation is succesful.
Otherwise, the built-in validation raises an error.
The validation error message can be customized using APEX Translation Text UC_IG_CHECKBOX_VALIDATION.
Use %0 to reference a column label and %1 to reference the invalid value.
You can see validation at work on this page. Set any column value to any value other than JONES, SCOTT and JAMES and save the interactive grid.