[Rd] HOME environment variable

[Gabor Grothendieck]

In 

http://cran.r-project.org/bin/windows/base/CHANGES.rw2010dev

there is a reference to the setting of a HOME environment
variable on Windows:

"R CMD / Rcmd now set HOME if unset, e.g. for use in Rcmd check."

Was this intended to be R_HOME?  Also, I don't understand the comment.
Could someone clarify it.  What is the use in Rcmd check referring to?

Finally, just in case it really does mean HOME, I have had problems 
in the past with multiple software systems (R was not one of them) 
all using HOME differently and conflicting with each other so if this
is a new use of HOME I would recommend that it be changed to a 
name that is not likely to conflict with other pieces of software.