[unboggling]

@davidfor & eschwartz, thanks, that clarified. @aleyx, thanks for commenting.

@kovid, thanks, that clarified. I'd never noticed in debug mode the uuid in the field inLibrary. And didn't understand what the menu command "match book" meant. But now it makes more sense to me.

@anyone, please evaluate these statements, are they true?:

In library view, Size (size) represents filesize of the largest format at the time book was added to library. Not editable. Adding or removing formats within calibre automatically recalculates it. But if user edits the format outside of calibre, size may not be accurate until the next time formats are added or removed in calibre or user resizes through Quality Check plugin. Usually accurate, but accuracy dependent on user.

In device view, Size (size) represents filesize of the format on device, whether sent there by calibre or not. Not editable by user. User could edit format on device (remote possibility). If calibre originally sent format to device, calibre matches by uuid and uses the filesize calibre remembers from before, not knowing about any device-side change of size; in that case, probably accurate unless user edited format outside of calibre. If calibre did not originally send format to device, filesize comes from the device; in that case, highly accurate. Accuracy depends on various factors, so interpret as approximation.

In library view, Date (date) represents when book was added to library. Accurate at that point. Editable by user. Subsequent accuracy depends on user.

In device view, Date (timestamp) represents when book was added to device, whether sent there by calibre or not. Not editable by user. Highly accurate.

(Not knowing exactly which fields are involved with the match book command in device view, I ignored those possibilities above. And I want to avoid parsing various conditional qualifiers out to infinite minute possibilities.)