Gloss on Ebooks, Libraries, and Feelies

While the distinction between accumulative and modular library became clear to me as I read the text, I think its characterization here is rather confusing. “Accumulative” is defined as “emphasizing the interdependence of component elements.” This suggest the idea of a system. But it becomes clear later that accumulative libraries are more like unstructured lists than like systems. As for modular libraries, they can be added to, so they do have an accumulative capability. It seems to me that the distinction boils down to encoding: in accumulative libraries objects are collected as they are; in modular libraries they are encoded in a uniform way. If this is the case, only digital libraries can be modular. But in a library of physical books the cataloging system creates an internal organization: does it mean that the library is modular?