What is "open-architecture-system"

Open-Architecture-System (OAS) is the main User interface and synthesizer software of the Wersi keyboard line. OAS improves on prior organ interfaces by allowing the user to add sounds, rhythms, third party programs and future software enhancements without changing hardware. Compared to previous organs which relied on buttons, OAS uses a touch screen to make programming easier. OAS can host up to 4 separate VST software instruments, allowing for an expandable system similar to the Korg OASYS. OAS can support dynamic touch and aftertouch, but cannot support horizontal touch like the Yamaha Stagea Electone.