When is a 100mm macro lens not a 100mm macro lens?

Although I've known that modern IF designed macro lenses change focal length as they focus, I haven't come across data which shows this. However here's a link which seems to, although I'm not sure where the info is sourced (the 70~180 is interesting):

http://xoomer.virgilio.it/ripolini/105_micro.htm

Also: http://xoomer.virgilio.it/ripolini/60micro.html

And: http://xoomer.virgilio.it/ripolini/70-180.html