ZAc - major currency

I am sending the following request

{
    "ExtractionRequest": {
        "@odata.type": "#DataScope.Select.Api.Extractions.ExtractionRequests.CompositeExtractionRequest",
        "ContentFieldNames": [

            "Currency Code"
        ],
        "IdentifierList": {
            "@odata.type": "#DataScope.Select.Api.Extractions.ExtractionRequests.InstrumentIdentifierList",
            "InstrumentIdentifiers": [

                {
                    "Identifier": "NL0011375019",
                    "IdentifierType": "Isin"
                }
            ]
        },
        "Condition": null
    }
}

I need to get the currency spot rates against EUR for the last 3 years. Usually we convert the small letters in the currency code to upper case and then construct an RIC code by adding "EUR=R". For example : if we need spot prices for GBp , we do GBPEUR=R.

However I see that, there is no data for the RIC code ZACEUR=R. The only available data for the currency pair is ZAREUR=R. (South African Rand). So how can we find the original currency for the RIC pair from the currency code of the ISIN , in this case ZAc ?