How to I limit a checkbox field to one choice? I am using a checkbox field to ca

How to I limit a checkbox field to one choice? I am using a checkbox field to capture a 'Y' or 'N' value. This works just fine unless the user checks both boxes. I tried a couple validation rules on the field but none have worked so far. Any suggestions?

a!checkboxField(
label: "Certification Required?",
labelPosition: "ABOVE",
choicelabels: {
"Yes",
"No"
},
choiceValues: {
"Y",
"N"
},
value: ri!newAgreement_cdt.certRequired,
saveInto: ri!selectedAgreement_cdt.certRequire
),

OriginalPostID-191699

OriginalPostID-191699