Period by consensus
Generally, only items considered period are really accepted at SCA events. A few (really useful) items are considered by some to be "in period by consensus" due to the fact that their omission would make life much more difficult and less fun. Items like this may include:
and many others.
Many (most?) places simply acknowledge that the items are out of period but use them anyway. In fact, marking them as "period by consensus" simply highlights their OOP nature and makes it harder to ignore them.
The term "period by consensus" itself would seem to be a limted regional usage.
This idea is less accepted in re-enactment groups. Most discourage such behaviour. During displays such activities are not permitted, and during events where they are not on display, only cigarettes make an appearance and then usually out of site. This is considered a minor inconvenience to a few and enhances the event greatly for many.