This option specifies the location of a mapping file designed to translate Windows NT domain group names to Unix group names. The file should reside on the Samba server. For example:
/usr/local/samba/private/groups.mapping
The file has a simple format:
UnixGroup = NTGroup
An example is:
admin = Administrative
The specified Unix group should be a valid group in the
/etc/group file. The NT group should be the name to which you want the Unix group to map on an NT client. This option will work only with Windows NT clients.