Jean, Thank you for your detailed summary of some of the thinking that went into the current sysfs-interface. Very much appreciated. I can hardly believe my good fortune in receiving such quick and thoughtful answers from you. And I apologize for mistakenly crediting you for the [0-255] choice for pwm range, thanks for setting the record straight. I don't want to take up any more of your time (right now anyway!). I accept the [0-255] pwm range as the way it is, and hope that I can soon contribute automatic pwm control for it87. Thanks, Frank