/sys$common/syshlp/helplib.hlb ASSIGN, Qualifiers, /NAME_ATTRIBUTES  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /NAME_ATTRIBUTES[=(keyword[,...])]

    Specifies the attributes for a logical name. By default, no
    attributes are set. You can specify the following keywords for
    attributes:

    CONFINE    Does not copy the logical name into a spawned
               subprocess; this keyword is relevant only for logical
               names in a private table.

    NO_ALIAS   Prohibits creation of logical names with the same name
               in an outer (less privileged) access mode within the
               specified table. If another logical name with the same
               name and an outer access mode already exists in this
               table, the name is deleted.

    If you specify only one keyword, you can omit the parentheses.
    Only the attributes you specify are set.