Rhinoceros is primarily a free form surface modeler that utilizes the NURBS mathematical model. Rhinoceros' application architecture and open SDK makes it modular and enables the user to customize the interface and create custom commands and menus.
Noun. 1. exigency-a pressing or urgent situation; the health-care exigency. crisis-an unstable situation of extreme danger or difficulty; they went bankrupt during the economic crisis.
Extensibility aka: Extensibility is a quality of computer software, programming language or protocol that takes into account the ability of future users to modify the existing system to their needs. Therefore, extensible computer systems are intrinsically designed to allow users to add or modify in ways that change functionality and outcomes.