Ever wanted to find an accent insentive expression like “bébé” in a column ?
Maybe you tried to list all possible accents. But Posix has the class for you, the list of éèëê could be refered as [=e=]
SELECT * FROM TAB WHERE REGEXP_LIKE(C,'b[[=e=]]b[[=e=]]')
not only [=e=] is easier to read and to type, but also it is more portable if you copy your scripts from DOS to UNIX and use different character sets