Since it is in terms of a %, to say 100 IRE as an absolute brightness is incorrect. So I set the brightness value to 100 (during calibration), use the black clipping point as an absolute minimum and adjust contrast and brightness to achieve a working gray scale that approximates the IRE range. But even b&w crt's from the 40's and 50's can blow you out. I realize this is all over the map with LCD monitors because they have a brightness value far higher than a crt and certainly paper white.
So far as the IRE connection, if you set up your monitor defining the lowest visible detail in the blacks then set the range to be defined by the whiteness you actually want, you wind up with 0 to 100% as the range of values. Now, every time I reconnect, I have to sign in. I've had it with this g.d.mn forum or rather, Jive.