OPINION — AG — AS TO A REAL ESTATE MORTGAGE WHICH SECURES PARTIAL PAYMENT OF A DEBT OR OBLIGATION THE MORTGAGE REGISTRATION TAX LEVIED BY 68 O.S. 1971 1904 [68-1904] IS TO BE COMPUTED BY THE COUNTY TREASURER UPON THE AMOUNT SECURED THEREBY. CITE: 68 O.S. 1971 1901 [68-1901] (MICHAEL JACKSON)