Use the GROUP command to indicate group ownership of the file being sent. Whether or not the GROUP is applied at the receiving host is implementation dependent.
Many systems, such as VMS and UNIX, for example, represent GROUP numerically in the filesystem. It is recommended that the numeric value not be used for GROUP, but rather the corresponding mnemonic whenever possible.
The syntax is
|group ID||is an installation dependent group identifier|
OWNER is a "meta command". It must follow a FILE command, should come before any DATA commands, and must preceed EOF.