I'm not sure that kind of relationship needs to be explicitly encoded. I'd think it would be sufficient to tag the items with the same <subject> and name/role="creator" information, and leave it at that.
Think about the library catalog. If we have two books by the same author, we don't manually create a "relationship" between the two books -- we just let the fact that they have the same author speak for itself, right?
From: Metadata Object Description Schema List <[log in to unmask]> On Behalf Of Talj Harper
Sent: Tuesday, January 8, 2019 11:25 AM
To: [log in to unmask]
Subject: [MODS] RelatedItem for Content Relation
Dear MODS Community --
I am helping on a project to migrate some old Dublin Core metadata into MODS, and I have found myself stumped over the <relatedItem> field. I have a series of letters that were listed in each others relatedItem field and I'm trying to figure out 1) what the relationship type is and 2) whether these really should be listed under relatedItem at all.
From what I can gather, the letters were originally listed as "related" because they share the same author, were written on the same day, and are about the same topic -- but sent to two separate people. The content of the letters, however, is not identical.
Looking at the type attributes for <relatedItem>, there really isn't anything that fits. I came across an older thread in the Listerv archive about how the <relatedItem> field was meant for bibliographic relationships rather than content relations, which may be my problem here.
Is there a way to keep this relation between the two letters in MODS? And, since I'm sure I will find more of these relations as I go through legacy metadata -- what, in general, is the best way to indicate a content relation between items?