The spec says
Reading Systems MUST NOT depend on the Unique Identifier being unique to one and only one EPUB Publication. Determining whether two EPUB Publications with the same Unique Identifier represent different versions of the same publication (see Release Identifier), or different publications, might require inspecting other metadata, such as the titles or authors.
I'm trying to figure out how to write a test for this—create two different books with the same unique ID and make sure that two books show up in the RS UI? Should this be normative text? In some sense this reads more like non-normative advice to reading systems. In general we say nothing about how reading systems present different publications to users, or how reading systems respond to updated versions of the same content.
The spec says
I'm trying to figure out how to write a test for this—create two different books with the same unique ID and make sure that two books show up in the RS UI? Should this be normative text? In some sense this reads more like non-normative advice to reading systems. In general we say nothing about how reading systems present different publications to users, or how reading systems respond to updated versions of the same content.