plane3d

I am attempting to fit a logistic regression plane to a 3-D scatterplot 
(which was generated using scatterplot3d).  I've noticed that the help 
pages of scatterplot3d include a function titled "plane3d."  However, 
when I attempt to use the function, I get the following message:

Error: couldn't find function "plane3d"

I've searched the archives and found no references to such a function.  
Is (or was) plane3d an actual function or is there just a typo in the 
scatterplot3d help page?  If it is a function, how would I tap into it?

Thanks.

Jim Milks
Graduate Student
Environmental Sciences Ph.D. Program
Wright State University
3640 Colonel Glenn Hwy
Dayton, OH 45435