Requested feature overview description.
A flag visible to and usable by accounts with approval permissions, indicating that a post was viewed and was neither approved nor deleted as it represents a borderline case and the opinion of other approvers would be helpful in making a final determination whether to keep or delete the post. A list of approvers who had flagged a post "borderline" would be displayed along the top of the post in a bar directly beneath the "post pending approval" bar.

Accounts which do not have approval privileges would not see the flag, nor who had used it.

This functions similarly to the "favorites" system, except rebranded for a different purpose and hidden from most accounts.

Why would it be useful?
It would clarify when a post had already been bypassed for approval by multiple janitors, making it more likely to be deleted rather than being allowed to timeout.

Deleting a post for not meeting the minimum quality bar improves communication to posters that their posts are not meeting the minimum quality bar, as opposed to allowing a post to timeout and appear to have been overlooked.

What part(s) of the site page(s) are affected?
Post pages.