"Format Model" is an Oracle SQL terminology for a string output or input format in functions that convert different data types from and to string values.
In Oracle, built-in functions, like TO_CHAR, TO_DATE, TO_NUMBER, accept string parameter called "Format Model", which can represent either input or output of such function.
Examples:
-- Convert date field to string
SELECT TO_CHAR(dateField, 'MM/DD/YYYY HH:MI:SS') from table1
Output: 01/01/1999 10:15:30
-- Convert string input to date
SELECT TO_DATE('01/01/1999 10:15:30', 'MM/DD/YYYY HH:MI:SS') from DUAL
Output: 01-JAN-99
