Most “codexes” are not bound at all.
Many do not even have ‘hard’ documents.
Your county’s official records system is termed a “codex,” and it consists of a number of “codexes” that are usually full of digital documents these days.
Codex mostly indicates an indexing system that permits easy access to specific pages or sets of pages.
I’ve already provided a citation demonstrating that your definition of a Codex is incorrect. Take it up with Daniel Webster.