OK thanks

I'll bookmark this thread for the section breakdown. I don't remember seeing that in the template help, or if it WAS there, it was more confusing than this example.
However when I try to use the code I get:
calibre, version 1.37.0
ERROR: Invalid template:
The template {series:.1:'ifempty($, field("title"))'}/{series}{series_index| [|] - }{title} ({authors}) is invalid:
string indices must be integers, not unicode