I'm not convinced. I'd have all the letters even if I hadn't bothered with the bars at all.
Needed earlier posters to show me where they are, admittedly, but the bars seem incidental.
Except they're mentioned in the title so must be important...but then "code" is in the last title but now we're told it's incidental.
I'm sure there's a explanation but this vague, unsatisfying, subjective endgame is sadly typical of Inquisitor under the current editor and is why it is no longer my favourite weekend crossword.