After an audit could not reconstruct why about a fifth of our roles sat at the level they did, we introduced a decision record. I'm at a regional bank in the US Southeast, about 3,100 employees, eleven levels.
It is one page with six fields: the role's purpose in two sentences; the three decisions the role makes without approval; two comparator roles already in the framework, one at the proposed level and one at the level below; the criteria that distinguish it from the lower comparator; who made the decision and on what date; and what would cause it to be revisited.
It takes about 20 minutes to complete. The comparator field has been the most useful, since it forces a relative judgement instead of an essay. Happy to hear what others would add or remove.