Syntax options:

    TO username | TO role-name | TO PUBLIC

    Specifies the user name, role name, or the PUBLIC user to which
    you want to grant the role. The PUBLIC user is the user name
    associated with all anonymous users who access the database.

    If the user name or role name exists as an operating system user
    or rights identifier, then Oracle Rdb will automatically create
    the user name or role name when you issue the GRANT statement.
    A role or user that is created automatically is IDENTIFIED
    EXTERNALLY.