@Felipe Chang Yesterday I found this:

['custrecord_nes_wo_tracking_create_prpo',<http://search.Operator.IS|search.Operator.IS>, true]

OR

['custrecord_nes_wo_tracking_create_prpo',<http://search.Operator.IS|search.Operator.IS>, 'T']

Is possible to have checkboxes that behave one way or the other.