Oracle Rdb stores information about the database as a set of
    tables called system tables. The system tables are the definitive
    source of Oracle Rdb metadata. Metadata defines the structure
    of the database; for example, metadata defines the fields that
    comprise a particular table and the fields that can index that
    table.

    The definitions of most system tables are standard and are likely
    to remain constant in future versions of Oracle Rdb.

    Under each Help topic for a particular system table, BLR refers
    to binary language representation. This is low-level syntax used
    internally to represent Oracle Rdb data manipulation operations.