Keysight U2722A Programmer's Reference Manual page 87

Returned Query Format
<NR1>
The returned value is the binary-weighted sum of all bits set in the register. For
example, if bit 5 (decimal value = 32) and bit 6 (decimal value = 64) are set, this
query command will return "+96".
Example
The following query command reads the Operation Status Event register.
STAT:OPER?
Typical Response: +96
See Also
STATus:OPERation:ENABle
*CLS
Keysight U2722A/U2723A Programmer's Reference
STATus Subsystem 10
87