Agilent Technologies N1996A-503 User Reference page 335

Bit Description
Bit Description
0, 1 These bits are always set to 0.
2 A 1 in this bit position indicates that the SCPI error queue is not empty
which means that it contains at least one error message.
3 A 1 in this bit position indicates that the data questionable summary bit
has been set. The data questionable event register can then be read to
determine the specific condition that caused this bit to be set.
4 A 1 in this bit position indicates that the instrument has data ready in the
output queue. There are no lower status groups that provide input to this
bit.
5 A 1 in this bit position indicates that the standard event summary bit has
been set. The standard event status register can then be read to determine
the specific event that caused this bit to be set.
6 A 1 in this bit position indicates that the instrument has at least one reason
to report a status change. This bit is also called the master summary status
bit (MSS).
7 A 1 in this bit position indicates that the standard operation summary bit
has been set. The standard operation event register can then be read to
determine the specific condition that caused this bit to be set.
Chapter 6
Using The Status Monitoring Subsystem
The Status Byte Register
335