Terminology Fail

Watched this Youtube video today [https://www.youtube.com/watch?v=V7JC0tHe7sY&t=728s] but as I'm very new to this hobby, I'm still learning occasional new acronyms and terms. I can't find GR-1 anywhere in the usual train terminology references. Wiki suggests its a hopper car, but is appears to be a special purpose kind of car of some kind and perhaps non-standard.

Any help?

Thanks...

GR-1 is the train identity for the carrier handling the train.

GR-1 would not be a typical train designation on CSX, but I found this under http://www.nakina.net/other/aartype" onclick="window.open(this.href);return false;:

GR - An open top car, having fixed sides and ends and level bottom with one or more hoppers dumping between rails or between and outside of rails.
In the basic system, G stands for gondola, H for hopper, F for flat, etc. The -1 may be an addition by CSX.

I just tried to go in on it to check something and can't make the link work. However, if you google "aar mechanical designations" it's at the top of the list, which is how I found it in the first place.

Video action is taking place in the Bone Valley of West Central Florida where phosphate is the main commodity being handled.

The Bone Valley is dispatched like no other territory on the CSX system. It is not done as normal Dark or Track Warrant territory. It is dispatched as a interconnecting series of Yard Limits as Yard Limits are defined in the CSX Book of Rules.

GR-1 is not a official CSX train designation, but most likely a local reference for a particular job. At various locations on CSX trains get referred to by their local reference, not their official CSX train designation. They will be referred to by their official CSX designation when copying Mandatory Directives from the Train Dispatcher.