- default.xml - Template used by some plugins to render web pages for this repository
- default_internal.xml - Fallback template to use to render web pages for this repository; usually symlinked to default.xml (New in EPrints 3.4)
- mainonlycss.xml - Additional template for very simple pages (no headers or footers, just the page title and content)
The files here are used for any language which does not have a more specific template installed in, say, eprints3/archives/ARCHIVEID/cfg/lang/en/templates/ (for English-language pages).
This directory does not exist in a fresh installation. You have to create it yourself to override the files in eprints3/lib/templates/.