5V signal pull-up/down VI curve

["Larp Lee" <larp_lee@qualitysemi.com>]

     Hello,
     
                I'm looking at the VI curve of PCI spec rev 2.1 version. In 
     section 4.2.1.2 AC specs, I'm trying to figure out how did PCI get the 
     equation Ioh=11.9*(Vout-5.25)*(Vout+2.45) for 3.1V < Vout < Vcc, and 
     Iol=78.5*Vout*(4.4-Vout) for 0V < Vout < 0.71V. I want to know the 
     boundary of maximum load I can have. Does any of you have answer for 
     these?
     
     Thanks,
     Larp Lee
ohU