This appendix contrasts two points of view:
The “paper” point of view, where digital objects of interest are like pieces of paper written and viewed by people
The “protocol” point of view, where objects of interest are dynamic composite protocol messages
XML is a very flexible technology. You can use it effectively for purposes that fit either of these points of view, even though its origin was in the paper (i.e., document) world. However, people accustomed to taking one point of view sometimes experience great difficulty in grasping the other. Even after they understand the other viewpoint, they tend to initially consider things from their accustomed point of view and assume that most of the universe ...