EXFO FTB-500 - Manual (Page 344)

Data Types
336 FTB-500
Applicable Data Types for Input—IEEE 488.2

This data type is used when units and multipliers have to be sent.
Examples: nm, kHz, km/s2, uW
A relative unit (dB) can be referenced to an absolute level, as shown on the
following diagram.
Examples: db, dbm, dBW
/
-
-
/
.
D/d B/b