Sorry if this has been asked before but I couldn't find it with a search.
I have finally started updating the series metadata since the number of books and series I have in calibre is getting larger.
When I enter the series name and number I am getting that plus a 1 in  so it looks like this.
Jax 1 
Jax 2 
Jax 3 
What is the purpose of the number in the brackets? I have preferences set to use roman numerals but that does not seem to do anything. Can someone explain the correct and best way to use the series field?