So it looks like there is no proper documentation on the arguments passed. So I will have to wing it. Support gave me this link:
http://www.retrospect.com/en/support/kb#script-hooks
and
http://www.retrospect.com/en/support/kb/script_hooks
gives a bit of information, but in logging with my own minimal
/Library/Application Support/Retrospect/retroEventHandler
it is passed a lot of arguments I shouldn't have to guess about...
-StartScript Copy Assistant - 2017-07-20, 3:31 PM 7/20/2017 16:36 /Library/Application Support/Retrospect/intv2775.reh
-StartSource Copy Assistant - 2017-07-20, 3:31 PM My Computer/Home /Volumes/Home/ My Computer /Library/Application Support/Retrospect/intv2776.reh
-EndSource Copy Assistant - 2017-07-20, 3:31 PM My Computer/Home /Volumes/Home/ My Computer 0 0 0 7/20/2017 16:36 7/20/2017 16:36 7/20/2017 16:36 Backup Clients/alpha-dhcp/OS/ada Normal My Computer 0 0 successful true
-EndScript Copy Assistant - 2017-07-20, 3:31 PM 0 0 successful
for example, what is
/Library/Application Support/Retrospect/intv2775.reh
it is not a file
and for example, what is
0 0 successful true
trying to tell me