I admit I am not a super technical genius when it comes to lighting, so I have no idea what IES textures are, and google searching doesn’t seem to be helping at all. I just want to know what they are, why they are important/awesome, and how Rocket uses them.
Thanks!!
These links should maybe be able to provide some background information and to help get you started:
2. Arqui9’s explanation, and an example of its use with 3Ds Max.
As for how to start applying IES into a Rocket pipeline, a dev will probably need to clarify the details on that. (Or if someone else discovers the means for this themselves, it’d be nice if they posted their results here! I’d certainly like to know, as well.)
I realize this isn’t a complete explanation, but hopefully it helps you. 
So what is the difference between these and light functions then?
With IES profiles you get the shape of light as it leaves the light fixtures or bulbs of manifacturers. This way you get easy to control, realistic results without bothering with light functions. To use, you just download the profile/s you want and then import it into the content browser like any other asset. Then load it directly to any light in your map(no materials or anything needed)
That is awesome!! And then you could use a light function to do flickering, for instance? Sweet thanks!!