Compatibility of SOCKETS(BS2000) V21.1 with earlier versions

SOCKETS(BS2000) V21.1 is compatible to all older SOCKETS(BS2000) versions, i.e. existing Socket user programs can be executed in version 21.1.

If a Socket user program was produced with the user library SYSLIB.SOCKETS.211 then it will not possibly run on systems with subsystem version V21.0 or lower.