To define a field using the DEFINE FIELD statement, you must have
    the Oracle Rdb DEFINE privilege for the database.

    If you have invoked the database with the PATHNAME specification,
    the field definition is also added to the data dictionary. Once
    you have defined a field globally, any relation can use the
    field definition by using the field name in the DEFINE or CHANGE
    RELATION statement.

    You can copy a shareable field definition from the data
    dictionary into the database.

    You must execute this statement in a read/write transaction.
    If there is no active transaction and you issue this statement,
    Oracle Rdb starts a read/write transaction implicitly.

    Other users are allowed to be attached to the database when you
    issue the DEFINE FIELD statement.