Complex sentence: The Codex's relationship to the Latin Vulgate was unclear and scholars initially were unaware of the Codex's value, which changed in the 19th century when transcriptions of the full codex were completed.
Split into simpler sentences: The Codex's relationship to the Latin Vulgate was unclear and scholars were initially unaware of the Codex's value. This changed in the 19th century when transcriptions of the full codex were completed.