Previous Hour Block Errors - Transmit direction.
Transmit is data from the network towards the customer.
Block errors are 12 millisecond time periods in which a
physical link level (e.g. DSL CRC or BPV) error occurs.
These errors are not the same as frame relay level errors.
This register is defined by Bellcore TR-TSY-000829.
Indexed by Bank.ChannelUnit.Port.Address