Referential constraint in On-Line 7

It seems that Informix On-line 7 supports cascading deletes when a referential integrity is violoated. When I create a foreign key constrait from dbaccess, it prompts me for "Add enable cascading deletes Yes or No". I chose Yes because I thought this would allow me to delete the referenced column without getting any error. But actually it does not work that way. I search all informix manuals, but didn't find anything about cascading deletes of foreigh key. Any comments are appreciated. Weimin