We introduce the calculus of concurrent nets as an extension of the fusion calculus in which usual prefixing is replaced by arbitrary monotonic guards. Then we use this formalism to describe the prefixing policy of standard calculi as a particular form of communication. By developing a graphical syntax, we sharpen the geometric intuition and finally we provide an encoding of these guards as causality in the prefix-free fragment, in the spirit of the encoding of the fusion calculus into solos by Laneve and Victor, proving that communication by fusion is expressive enough to implement arbitrary monotonic guards.