Regeneration Codex
From Tardis Wiki, the free Doctor Who reference
The Regeneration Codex was stored inside the Urn of Rassilon in Alcove 5-Δ-7-9 of the Omega Vault. It was an ancient artefact the purpose of which was shrouded in mystery. The Eleven left Gallifrey with it in a stolen TARDIS. (AUDIO: The Eleven)