  Discursive knowledge emerges as codification in flows of communication. The
flows of communication are constrained and enabled by networks of
communications as their historical manifestations at each moment of time. New
publications modify the existing networks by changing the distributions of
attributes and relations in document sets, while the networks are
self-referentially updated along trajectories. Codification operates
reflexively: the network structures are reconstructed from the perspective of
hindsight. Codification along different axes differentiates discursive
knowledge into specialties. These intellectual control structures are
constructed bottom-up, but feed top-down back upon the production of new
knowledge. However, the forward dynamics of diffusion in the development of the
communication networks along trajectories differs from the feedback mechanisms
of control. Analysis of the development of scientific communication in terms of
evolving scientific literatures provides us with a model which makes these
evolutionary processes amenable to measurement.

Computers and Society;Digital Libraries;Physics and Society