i - to ignore case
c - to match case
n - to make the metacharacter dot symbol match new lines as well as other characters (more on this later in the chapter)
m - to make the metacharacters ^ and $ match beginning and end of a line in a multiline string (more, later)
The default is "i".
The following example finds the "s" and match case.
SQL>
SQL> SELECT REGEXP_INSTR('This is a test for printing SS','s',1,1,0,'c') position
2 FROM dual;
POSITION
----------
4
SQL>