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

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.