Forum OpenACS Improvement Proposals (TIPs): Re: TIP #66: (Proposed) Standards for Internationalizing Content

a cr_child_rel is for an item that should not really exist independent of the parent (an example would be the collection of images photo album creates for a single photo) and an cr_item_rel is for relating two items (like relating an author bio to an article for example); things related via cr_child_rel should be deleted when the parent is deleted but for cr_item_rel deleting one item should not affect the other.
Then cr_child_rel seems more appropriate for localizations.  By analogy to acs-lang, messages can't exist for a locale unless the message key exists for en_US.  For i18ned content, we will have the same thing except that the parent item could be of any locale, not just en_US.
This is also analogous to the use of folders. You could say that each content item "contains" all its localizations.