It was two different guys from two different maintenance organisations involved in this.
I'm surprised that a B1 Engineer wouldn't know what ppm meant, but it's really scary that the engineer at LGW was unable to use Airnav, pretty much everyone I know and have worked with can happily switch between Airnav and AirnavX. (personally I'm not a fan of AirnavX).
It's quite easy to screw up the effectivity in the A330 & A340 manuals in Airnav but this is due to the different weight variants, the A320 should be fairly straightforward so I've no idea how he ended up using a manual for a NEO.