80/20 - companies vary in philosophy on this. It has acquired the name 'alpha-floor' in Boeing land which I am sure is an AB term and 'alpha-floor' it is not IMO.
Personally I forgo the 'min speed' value of using it and its main benefit for me is in its giving an automatic g/a power application of a REDUCED setting, with the option of a second press to get FULL, whereas the 'rules' (bless 'em) require FULL g/a power for any manual throttle g/a.