The book-in-timeness

A book-in-time is a particular understanding of books as objects published in a specific moment in time. The in-timeness of a book states its static place on the timeline and defines two directions which in turn shapes the book as an open container of all the knowledge of the past as well as the future ones.

LEFT > Potentially it could contain all the references to all possible knowledge existing before it, but not after. Its content points always on the left side of the timeline. The same can be said about quotes because a book can quote only things that happened before its publication.
RIGHT > Annotations (in the book-in-time) are the other side of the timeline, they are always been done after its publication. Annotations (in the book-in-time) are all the possible links starting from the book's date of publishing and pointing to the future.

When you read and annotate a book, you are like a pendulum, freely swinging between the in-timeness of that particular book (and edition), between its links to the past and its links to the future that you are writing. In this context, the annotation is an essential part of the process of dematerialization of a book, if not the motor.

The concept of book-in-timeness can be the only way to deal with the dematerialization of books in the digital format.
It is a way to point what a book is (or was) by highlighting:

what was the book in the very moment of the publication (which can be considered as the source) - the central point of the timeline (book-in-time)
what was its possible world of references - the left side of the timeline
which is the process of its dematerialization (to be discussed in 'the living book') until the current moment - the right part of the timeline

We can argue that a shadow library, opposed to a library, tends to tack the pendulum toward the right side of the timeline, which means to allow a reading of the text, conscious of the possibility of greater distance from the book-in-time(source) and its world of references.