This is what the database structure looks like now:

----mariage
    [mariage.rng, mariage_drama.rng]
    ----anthology
        ----images
        ----texts_original
    ----editorial
        ----articles
        ----intros
    ----back_matter
        ----references
        ----biblio
    ----translations
        ----texts_modern

ALL xml files are at the bottom level (two levels below the root). This means that when you link to RNG files, at the top of your document, you'll need to do it like this:

<?oxygen RNGSchema="../../mariage.rng" type="xml"?>
<?oasis-schema href="../../mariage.rng" type="application/xml"?>

This means "go two directories up the tree to find the file". ../ means "go up one directory", and two of them means go up two. The value of this is that we only have ONE copy of the schemas. This is important because at some point I'll be rebuilding the schemas, and I only want to replace them in one location, instead of dozens. Don't make any copies of the schemas anywhere else. If you try to validate your document and it doesn't find the schema, that means either your document is in the wrong place, or you don't have the right path (as above) in the head of your file.