Compaq DS20E - AlphaStation - 1 GB RAM User Manual page 177

NOTE: The term "operating system selection," as it is used in this context, refers to
a version of Windows NT. It does not pertain to the DIGITAL UNIX and
OpenVMS operating systems.
Each operating system selection is a set of information for a version of Windows NT.
It describes the disk and partition containing the OSLOADER.EXE file associated
with a particular operating system installation, as well as the path to the operating
system itself. In addition, the operating system selection contains any options passed
to the operating system during boot.
By default, one operating system selection is displayed on the AlphaBIOS Boot
screen for each operating system installed on the system. It is not normally necessary
to modify operating system selections, since the Windows NT installation creates
and modifies operating system selections as needed. If you add SCSI controllers
after the installation of Windows NT, it may be necessary to modify operating
system selections. Depending on what kind of SCSI controller is added, in which slot
it is placed, and where its driver is in the startup order relative to other existing
controllers, the disk numbering may change and modification of operating system
selections may be required.
AlphaBIOS Console 5-35