VMS Help SET, DEVICE, Qualifiers, /SITE  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /SITE=(n, logical_name) (ddcu: DSAnnnn:)

    Indicates to the shadowing driver the site location of the shadow
    set member or of the shadow set (represented by its virtual unit
    name). Prior to using this qualifier, you can define the site
    location in the SYLOGICALS.COM command procedure to simplify its
    use.

    The valid range for the site location designator, n, is 1 through
    255.

    The following example shows the site locations defined, followed
    by the use of the /SITE qualifier:

    $ DEFINE/SYSTEM/EXEC ZKO 1
    $ DEFINE/SYSTEM/EXEC LKG 2
    $!
    $! At the ZKO site ...
    $ MOUNT/SYSTEM DSA0/SHAD=($1$DGA0:,$1$DGA1:) TEST
    $ SET DEVICE/SITE=ZKO  DSA0:
    $!
    $! At the LKG site ...
    $ MOUNT/SYSTEM DSA0/SHAD=($1$DGA0,$1$DGA1) TEST
    $ SET DEVICE/SITE=LKG  DSA0:
    $!
    $! At both sites, the following would be used:
    $ SET DEVICE/SITE=ZKO  $1$DGA0:
    $ SET DEVICE/SITE=LKG  $1$DGA1: