What does a GenFly look like??

I usually post on the historic aviation forum,so be gentle with me! The RAF have recently taken on a number of Eurofighter maintenence simulators,known for some reason as GenFlys. They’re apparently quite serious peices of kit,so much so that they’ve been given RAF serial numbers (in the ZJ??? range IIRC).
What I would like to know is,what does one look like? Is it a complete static airframe?Also,what is the meaning of the name?