Headwind and Tailwind in Takeoff/Landing Performance
I need a clarification. I read the CAA safety leaflet 07 pertaining to airplane performance for general aviation. It says if there is an adjustment that can be made for wind, only 50% of the reported headwind and 150% of the tailwind should be considered to account for variables. Now, what confuses me and I was told this before, is that most performance graphs account for this "rule". I have looked through several AFM for different manufacturer and I have not found any reference to it. My question is:
1) Do performance graphs/tables, include those factors? Which manufacturer have included them?
OR
2) Should we simply account for no more than 50% of the reported headwind and 150% of the tailwind and plug this in the graphs or tables to find the takeoff or landing performance?