Help with Calculation

[Jeremy369690523jsm]

I have a PDF form with a Field formatted as a "Check Box".  If the box is checked I want another Field to auto populate as "A". If the box is not checked I want the other Field to auto populate as "B". I know very little about all this but I'm guessing I should be able to do it on the "Calculate" tab of the Text Field Properties...HELP PLEASE

[try67]

Yes, as the Calculate script of the text field enter the following (adjust the field name as needed):

event.value = (this.getField("CheckBox").valueAsString=="Off") ? "B" : "A";