Tuplix Calculus Specifications of Financial Transfer Networks
  We study the application of Tuplix Calculus in modular financial budget design. We formalize organizational structure using financial transfer networks. We consider the notion of flux of money over a network, and a way to enforce the matching of influx and outflux for parts of a network. We exploit so-called signed attribute notation to make internal streams visible through encapsulations. Finally, we propose a Tuplix Calculus construct for the definition of data functions. 
J.A. Bergstra, S. Nolst Trenite, M.B. van der Zwaag