You are right, embedding a dependent object (AttachmentFolder or TextCollection) is the way to store data longer than 255 characters in a business object. The restriction to 255 characters applies to the element declaration and is independent of the data type:
businessobject LongTexts {
element LimitedText255 : LANGUAGEINDEPENDENT_Text; // or any other unrestricted type, e.g. Name, Identifier, Note, ... [DependentObject(TextCollection)] node CapableToStoreLongTexts;
}
Regards
-- Reinhold