CVS working now, but why?

[Gerson Kurz]

I managed to update my CVS tree, but not by the method described on 
http://www.winehq.com/devstart.shtml, that is

export CVSROOT=:pserver:cvs at cvs.winehq.com:/home/wine
cvs login
cvs update -PAd

but rather by doing this

cvs -d CVSROOT=:pserver:cvs at cvs.winehq.com:/home/wine login
cvs -d CVSROOT=:pserver:cvs at cvs.winehq.com:/home/wine update -PAd

which, if the documentation has anything to say, is the same. And yes,

echo $CVSROOT

reports the correct server (winehq.com). Same thing also works seamlessly 
for rhlx01.fht-esslingen.de. Can somebody please explain? (or point me to a 
group that discusses CVS matters as I'm new to this. And silly me thought 
VSS was difficult to maintain...)