We define a new notation called netcharts for describing sets of message sequence chart scenarios (MSCs). Netcharts correspond to a distributed version of High-level Message Sequence Charts (HMSCs). Netcharts improve on HMSCs in two respects.

• Netcharts admit a natural and direct translation into communicating finite-state machines, unlike HMSCs, for which the realization problem is nontrivial.
• Netcharts can describe all regular MSC languages (sets of MSCs in which channel capacities have a finite upper bound), unlike HMSCs, which can only describe finitely-generated regular MSC languages.