From the How to Transcribe page: "Preserve original spelling, punctuation, grammar, word order, and any page numbers or catalog letters or numbers. ... If a misspelling will impact the searchability of the document, use a tag to add the correct spelling."
Just a reminder about this because I had to fix a transcription that started with: "(N.B. There are multiple misspellings which I've corrected for ease of reading.)" Also, transcribers shouldn't add their own notes in the transcription. That's another thing you can use tags for.