The OS/2 Subsystem for NT subkey stores basic software
information for the Microsoft OS/2 version 1.x
subsystem. The OS/2 Subsystem for NT subkey contains
several subkeys but, by default, only the config.sys subkey
contains an entry. When an OS/2 program has been run on the system,
the config.sys subkey contains configuration information for OS/2.
Until then, this subkey contains a single entry that serves as a
placeholder.