Calc Builder field type: Yes / No

Yes / No is a single check-box. Ticked returns Y, unticked returns an empty value.

In code

if ($newsletter === 'Y') {
    $discount = 5;
}

Use it for opt-ins, “include VAT”, “add insurance” and similar on/off switches.

Part of the Form Fields reference. All types are demonstrated together in the Field Types Showcase.