Variable Declaration

Variable Declaration

Hello,
     I was able to get the show/hide fields to work with a check box.  Now when trying to show/hide fields using a drop down box response, should I claim the variables at the beginning of the Form Definition?  I know they are localized instances, but in declaring them onload, will I need to also declare them at the instance point?  Or would it just be the reference in the on input if/else?  Thank you.