Dear all, thank you very much for all the suggestions. The outline on how much longer LS3 will be supported and that LS5 will soon be the new standard as well as the official implementation of this functionality in LS5 provides confidence, that an upgrade might be the best way to solve our problem. We hope we can test this functionality in the holiday season. Thank you as well for the suggestions with the font and the notification: we already chose a font that distinguishes at least "O" and "0" well, but often respondents do not have a comparison (only a single character of those two appears in the token) so the confusion persists. We added the suggestion to try "O" or "0" (and "I" "1", "l" respectively) if a wrong token was provided and hope to catch some frustration already with this step.