This is a tale of two psychological Types; they share a temperament group, but different Interaction styles. They also have similar but opposite cognitive function stacks.
Pat, a lecturer and non-fiction author, has preferences for INTP. Jan, a programmer and student in one of the areas Pat writes about, has preferences for INTJ. Jan has been reading one of Pat's books and longs for a more easily portable copy. So, Jan writes to Pat, asking if any thought has been given to making an ebook available at some point.
Pat responds, saying the book is considered to be a workbook, not a textbook, so it really needs to be in paper format.
Jan writes back, acknowledging the workbook but commenting that readers don't always view books in the same way the author meant. As a reader, Jan views the book as a reference text; it's the reference material Jan wants to be able to refer to readily in electronic format.