Work efficiency units can be exchanged for work efficiency coupons.
1 work efficiency unit = 1 work efficiency coupon. An exchange may be performed in both directions. During the exchange, work efficiency units are collected from the canteen and, in return, coupons appear in the bag of the given clone.
If, for any reason, coupons are no longer needed, they can always be exchanged back into work efficiency units, in which case, these coupons will be written off, after which work efficiency units will appear back in the canteen again.