REGEXP_LIKE To Find Unwanted Characters

This SQL will search for filenames that contain characters other than

1. a-z
2. A-Z
3. 0-9
4. underscore
5. parenthesis
6. dash
7. period
8. square brackets

SELECT ATTACHSYSFILENAME 
FROM PS_LON_TBL
WHERE REGEXP_LIKE (ATTACHSYSFILENAME, '.[^][a-zA-Z0-9_()-.]');