I'll admit that I have no idea what I'm talking about w/r/t LGR, but it seems to me that "dial down" is exactly what the function does.
Tony mentioned that it is "automatic". I don't think it can be fully automatic; the minimum target level has to be defined to z/VM (and I had wondered whether it could be defined to z/VM on a per-guest basis). So imagine a z/VM definition while running on a z14: Guest G is to be able to use LGR to a z13. Now you IPL z/OS as guest G. z/OS would see the facilities available as those for the z13. A program would see the facilities available as those for the z13 (I assume). Isn't that what you would think "dial down" should do? Peter Relson z/OS Core Technology Design
