[Samba] Share permissions

[João Amâncio Ferreira]

Hello all,

I have a SAMBA share called "share_a" and it is working fine (below is a 
snapshot of it):

[share_a]
path = /shares/share_a
browseable = no
valid users = @group_a @group_b @group_c
write list = @group_a @group_b
read list = @group_c
create mode = 777
directory mode = 777

Inside this share there's a lot of sub-folders.
The problem is: How can I give to one of these folders permission to a 
restrict group, like "group_d" that others (group_a-c) won't be able to 
browse/read/write?

SAMBA version is: 3.0.20 and it installed as default Slackware 10.2.0 setup.


Thanks and sorry by the english,

João Ferreira