NFS - exports syntax

[marco.borsatino at poste.it]

Hi to all.
My problem concerns NFS configuration. I'm trying to simulate a little network using Sun VirtualBox in a Windows host and most of operations work fine, but I've some problems with /etc/exports syntax.
This is my current exports file:
--
/cond1 /cond2 -mapall=user1 pc01 pc02
/usr/home -alldirs pc01 pc02
---
When I type:
#showmount -e
I get
/usr/home         pc02 pc02
/cond1            pc01 pc02
/cond2            pc01 pc02
which is ok. But I wold like to use different "mapall" options for different filesystems; for example, something like this:
/usr/home -alldirs        pc02 pc02
/cond1 -mapall=user2 /cond2 -mapall=user1 pc01 pc02
which does not work: only /usr/home is exported. Or
/usr/home        pc02 pc02
/cond1 -mapall=user2 pc01 pc02
/cond2 -mapall=user1 pc01 pc02
Only /usr/home and /cond1 are exported.
FreeBSD exports man page states:
"Each line in the file (other than comment lines that begin with a #) specifies the mount point(s) and export flags within one local server file system for one or more hosts.". So, is it impossible to export different directories to different users using mapping?
Thanks. Sorry for my bad english.
Marco