In programs, the READY statement explicitly declares your
    intention to access one or more databases and causes an attach
    to the database. READY is not available in RDO.

    You do not have to use READY to access a database. A database is
    readied automatically the first time you refer to it. However,
    you do need an INVOKE DATABASE statement.

    If you issue a READY statement without specifying a database
    handle, Oracle Rdb opens all databases declared in that module.