Ahh no thats something different
Well look theres a directory on the iso called "FIELD". This directory simply is a list of filenames that belong to the category field. However that does not mean that all those files are actually in any kind of order on the image. If you look at the lbas you see that the field directory is a total mess. Thats why - when I wanna update all dat and bsx files inside it - I have to update every single file manually.
Cdmage already has the quite advanced option of automatically extracting the whole Field folder at once so it really searches all lbas and extracts the files. Unfortunately this does not work vice versa. This would require some programming...