Lighting & Custom Content

[TheGreatCthulhu]

Or from wiki
The normal map for the material and uses the standard format rgb = xyz and is in tangent space. Note that this needs to be converted to a format of XY only though (3dc)!

Not an artist so what it means? no clue

I think it means that the game uses compressed normal maps.
Since normal vectors are all unit length, and taken to be in tangent space, you can throw out one component (z).

I think it needs to be compressed/exported in 3Dc format, also known as BC5.
For example, NVIDIA texture tools include a command line tool that does this, using:
nvcompress -bc5 inputFileName outputFileName

Can be found here: https://developer.nvidia.com/gpu-acceler...ompression

There could be some GUI tools out there as well.