Group administration in POSIX corresponds to that in UNIX. It differs from group administration in BS2000 in the following ways:
In POSIX, the sole function of groups is to distribute access permissions to files. In BS2000, groups also serve to control the use of resources, such as disk storage, computer power etc.
In POSIX, a user can belong to up to 16 groups simultaneously, whereas in BS2000 a user may only belong to one group.
BS2000 groups are arranged hierarchically, but this feature is not available in POSIX.
A user can change the current group in POSIX, whereas this is not possible in BS2000.
Because of these substantial differences, POSIX and BS2000 groups exist side by side but are administered separately: the POSIX groups on the shell level, the BS2000 groups on the BS2000 level. This corresponds to the different protection mechanisms of POSIX and BS2000 files.
If the hierarchy is omitted, POSIX and BS2000 groups can be defined identically, i.e. they then contain the same users.
For further information on group administration, please refer to section “Administering BS2000 and POSIX groups”.