I am writing a carbon accounting Web app.
Carbon tokens are non-negative integers. Tokens always go in pairs: a non-retired token and a retired one. The corresponding retired token is obtained from non-retired by adding one. The non-retired ones are always even, retired ones are odd.
A token may have a name, but may go nameless.
How to present a user to choose a token?
If I list all the tokens, the user may confuse which are retired and which retired one corresponds to non-retired one.
I can add checkbox "Show retired tokens" and show a list of either non-retired or retired tokens dependently on the checkbox. But this way the user may also not understand which retired corresponds to which non-retired. Maybe, I should show the non-retired token number in parentheses, when listing a retired token, and vice versa?
The task is simplified by that the usual number of tokens for an organization is just 2 (one non-retired and one retired), but this may not always be the case.