Previous Hour Severely Errored Seconds - Transmit direction.
Transmit is data from the network towards the customer.
Severely Errored Seconds are seconds in which three or more
block errors occur. These errors are measured at the physical
link level (e.g. DSL CRC or BPV errors) and not at the
frame relay level. This register is defined by Bellcore
TR-TSY-000829. Indexed by Bank.ChannelUnit.Port.Address
(note: DDS loops cannot detect transmit errors)