Practical capabilities: Prototype structure is exposed in the user interface. Among other things, the scheme supports replacing parts of any item with functionally equivalent elements in the repository via prototype swapping, and editing the properties of both instances and prototypes. A swap sequence:
Hybrid construction: Diagrams or drawings can be built in the user interface, by code, or from data, and then extended and modified in the interface.
Open source foundation. The core of the system, including the implementation of prototype trees, and their graphical realization via SVG, is freely available under the MIT license. Here is its GitHub repository.
Development stage: functional proof of concept (pre-beta)