[matplotlib-devel] What is rcParams['units'] for?

While investigating the imshow problem reported today by Emanuale 
Passera (a problem that seems to have been fixed, though I don't know 
when or how), I stumbled across the verbose-helpful report of the 
"units" rcParams entry.  Sure enough, it is in rcsetup.py and in 
matplotlibrc.template, but a quick code scan turned up no evidence that 
it is used anywhere.  Is it vestigial, and a candidate for surgical removal?

Eric