Thanks i will check this out.
My target is simple.
I have series which belong all to a main series called "Perry Rhodan" Those are booklet series which go up to 3000 books. For those i need series index up to 4 digits.
All other series won`t have more than 99 books but sometimes floating index like 10,50.
That`s the only reason i wanted to have a contain syntax which checks if the series contains Perry Rhodan.
But i will check out your suggestion, even i have to cluster the opf file with an other custom column. With a content syntax this won´t be necessary
On the other hand as i read the same book sometimes on different devices, the "long index number - author - title" file name gives as quiet unique name to prevent mistakes in synchronization of reading position with Moon-Reader
Ah, is there a way to transform for example a series name "I Want All" to "IWA" ? Using only the first letter of each word?