Bluecharts have FID, PID, RgnID, VenID
so they can have the same FID but different RgnID VenID. These numbers vary according to chart coverage- PID is always 1.
If FID is less than 2200 you can use JM and .unl made in JM advanced mode and using also PID, RgnID, SubregionID (alias improperly called in JM vend ID) or all the BC features wont be unlocked.
If FID is greater than 2200 JM wont work.
Be sure to have the latest firmware in your GPS, because newer Bluecharts in some devices need new firmware