This EPICS database implements two additional records per EPICS scaler channel.
The for scaler channel 2 the records are

  $(P)$(S)_Dark2.VAL   - Dark current per second for scaler channel 2.
  $(P)$(S)_SD2.VAL     - The dark current subtracted value for scaler2.

where $(P) and $(S) are defined to have the same values as in the standard
Jscaler.db database.  The database is loaded into the EPICS VME crate by
adding a line to the 'st.cmd' startup script that looks like

dbLoadRecords("iocBoot/ioc1/Jscaler_dark.db","P=s10id:,S=scaler1,C=0", top)

Please note that this database contains a definition for the scaler record
$(P) and $(S) itself and thus is not immediately compatible with the standard
Jscaler.db database.  This is due to the fact that EPICS does not supply
any way for an add-on database to add forward links to existing records.
If you wish to combine Jscaler.db and Jscaler_dark.db, the simplest way
is to merely move the FLNK field whose value is "$(P)$(S)_cts1.PROC" in 
Jscaler.db to the LNK4 field of Fanout record "$(P)$(S)_fan0" defined
in Jscaler_dark.db.

Hopefully, something equivalent to the dark current fields in Jscaler_dark.db
will be added to some future version of Jscaler.db.

William Lavender