This
chapter describes the concepts related to installing, upgrading,
and updating OpenVMS operating system software and layered products.
Two methods are available for installing or upgrading software:
the POLYCENTER Software Installation utility and the VMSINSTAL.COM command procedure.
To install or upgrade layered products, use either the POLYCENTER Software Installation utility or
the VMSINSTAL.COM command procedure. Each layered product is packaged
to use one of these. Refer to the layered product's documentation
for information about which to use.