Well that changes things ALOT. So teams are allowed to use the reference maps from all the teams with the same engine. I smell a huge hole in the regulations. You could spread the mapping much more then 2% by this if all teams with the same engine work together.
Lets take an example: Renault is supplying 4 teams with engines, meaning there are 4 different reference maps that can be used. Lets also assume there is 1 big engine map, then those 4 teams can deviate from it, in a continuous manner, in this order:
-team1: -2%/2%
-team2: 2%/6%
-team3: 6%/10%
-team4: 10%/14%
-->all teams can deviate between -2% to 14% and can select a map at any point between that range, because they are allowed to use 4 different reference maps.
Teams could deviate even further, but then it would mean you are no longer deviating from it in a continuous manner.
It will be interesting to see how teams are going to select their reference maps for next year.