From: "Robin Wendler" <[log in to unmask]>
> Did the MODS schema authors consider making more of
> the MODS subelements global elements, and "ref-ing" them
> within the larger elements such as originInfo?
All the top-level elements will be global in version 3, so by "more" I assume you mean the subelements.
We considered it and we didn't give it as much consideration as the idea probably deserves. It seemed simple to externalize the top-level elements because they're mutually independent (not entirely, but almost) while subelements either (a) exist in the context of their parents so they would be referenced "out-of-context" so to speak, or (b) are so simple that externalizing them wouldn't serve any purpose and would complicate both schemas (MODS and the referencing schema).
>....  such as publisher and frequency.
Publisher is defined as:

       <xsd:element name="publisher">
       <xsd:documentation>260 $b</xsd:documentation>

So what would a schema gain by referencing the MODS publisher element? The marc  mapping semantics?  Is that worth it?  Frequency is similar.
I do think it would be worthwhile to identify the elements that are appropriate for external reference, and making them global wouldn't be a big effort.
> The usual apologies for asking dumb questions apply. 
(Hardly a dumb question, Robin.)