U1231A/U1232A/U1233A User’s Guide III
Safety Symbols
The following symbols on the instrument and in the documentation 
indicate precautions which must be taken to maintain safe operation of 
the instrument.
DC (Direct current or voltage)
AC (Alternating current or voltage)
Earth (ground) terminal
Caution, risk of danger (refer to this manual for specific Warning 
or Caution information)
Equipment protected throughout by double insulation or 
reinforced insulation
Category III 600 V overvoltage protection