Unlike an cursor variable, which refers to different work areas, a explicit cursor refer always to the same query.
DECLARE
CURSOR Vc_emp IS SELECT * FROM EMP;
BEGIN
...
END;
CURSOR low_paid (num PLS_INTEGER) IS
SELECT empno
FROM emp
WHERE rownum <= num
ORDER BY sal ASC;
OPEN myCursor;
LOOP
FETCH myCursor INTO myRecord;
EXIT WHEN myCursor%NOTFOUND;
END LOOP;
CLOSE myCursor;
where: