altering constraints

Howdy I currently have a table that has this check on it. I am using informix 4gl 7.2 check ((bank_acct_suffix matches '[0-9][0-9] ') or (bank_acct_suffix matches '[0-9][0-9][0-9]')), I want the simpliest way to extend it to include : or (bank_acct_suffix matches '[0-9]') As you can tell I'm new at this. Thanks for any help.