[enonod]

I only persist with my questions because so many answers/postings in this forum contain phrases such as "I believe", "I presume", "probably"; not because I wish to fire argument.

@DoctorOhh: Thank you for your response and effort.

True, Unless you do a conversion or go out of your way using Polish or Modify Epub plugin the metadata in books are updated upon export from the calibre library. It is explained well in post 3.

I confess that I missed "...but not in the base format" in post #3.

Are the books moved or is the folder simply renamed? I'm guessing the folders are simply renamed by the OS. If that OS process requires a "move" it is still a single entry in the allocation table not actually moving a large file. Either way these are a blink compared to expanding a book writing to it and re-compressing it.

I refer to my comments to BetterRed below regarding multiple books, one author and the various types of file system.

Keep in mind the old opf files have nothing to do with calibre storing metadata for books. These files are used to restore the database in case of database corruption.

I was obviously mistaken in thinking they were 'like' sidecar files that carried what was 'not' in the book and that it was part of the ePub standard that every book has one.

eBooks are obviously a very complex subject.

@BetterRed: Thank you for your response and time obviously taken.
I am not expecting to turn this into a controversy but I do not fully agree with you although your (b) is an interesting point.

i.e they want the RAW kept in the same state as it left the camera.

I accept regarding RAW but it is now becoming the norm, however most photo's kept in database are not RAW but JPG or otherwise and there is no 'contamination'. It is standard practice, especially with journalists and the like and in fact it is necessary in order to copyright, watermark and provide the receiving potential buyer with keywords describing the content. Sidecar files are now tending to be used only where the original cannot be written to and until recently this applied to all RAW files and for a few it is still true.

With advanced file systems, eg NFS, HFS+, NTFS etc, when a folder (directory) is renamed (or moved within a device) it all happens within the file system index/directory/master file table structures. The contents of the folder are not moved, so a folder containing 200GB of data can be renamed just as fast as folder with 2KB can be. This is not true of primitive file systems such as FAT or BDOS.

Can you confirm categorically that an author folder containing sub-folders for each book, does not result in moving a single book or its folder if the author name is changed for that book only (such that the book must then become a sub folder of a different author folder)? It does not require renaming the title is the same.
I think you are suggesting that manipulation of File Allocation Tables in Windows (whether the Calibre owner is using FAT, FAT32, NTFS or whatever) is all that is required to have the folder appear elsewhere in a different hierarchy, which action is of course hidden from the user (who thinks the folder was physically copied and then the original deleted).