I find it virtually impossible to read an xml schema, so want to
confirm something:

Is it the case that things like the title element are defined in such a
way that foreign markup can be added?

So, the following is valid?

        <title>some <foo>title</foo></title>

I ask because I was recently reminded about this issue of inline
markup, and according to my Relax NG-based setup, the above is indeed
valid. If that's correct, then perhaps one solution is to use
namespaces to handle this. E.g.:

        <title>some <eb:citedtitle>title</eb:citedtitle></title>

        <title>some <eb:quote>quote</eb:quote></title>

        <title>some <eb:soCalled>phrase</eb:soCalled></title>

... and so forth. I still think MODS ought to have a span element for
this stuff though.

Bruce