All properties for the request object are listed in the Direct Service Request page.
The sample below provides the specific fields required by the reversal use case.
{
"serviceType": "REVERSAL",
"customer": {
"id": "567899"
},
"card": {
"accountNumber": "5400000000000000"
},
"transaction": {
"amount": 123
},
"original": {
"responseCode": "00"
}
}