/WRITABLE=[GALAXY[=IDENT]]
       /NOWRITABLE

    Installs the file as a writable known image when you also specify
    the /SHARED qualifier. The /WRITABLE qualifier applies only to
    images with image segments/sections that are shareable and
    writable. The /WRITABLE qualifier is automatically negated if the
    /NOSHARED qualifier is specified.

    On Alpha, you can use the GALAXY keyword with the /WRITABLE
    qualifier to place write shared image segments in Galaxy global
    sections. You can also use the IDENT keyword with GALAXY to include
    the image ident in the name of the Galaxy global section, so that
    multiple versions of an image can be used simultaneously in a Galaxy
    system.