Cities evolve over time and their evolution is often studied using material objects and historical documents. Based on available evidence, researchers propose various hypotheses explaining the probable evolution, both imaginary and factual. Furthermore, city models are used to model and visualize 3D structures and semantic information of the cities. With the help of versioning of city objects, it is possible to represent temporal changes of city structures. And with the support for representing scenarios, it is possible to represent different possible sequences of urban changes. In this article, we formalize a set of rules for representation of concurrent points of view of researchers related to urban changes based on standard city model. The goal is to understand how the cities have evolved, what were the key changes and allow exchange between various hypotheses (or processes). We developed a proof-ofconcept named UrbanCo2Fab based on these rules to demonstrate the highly potential use cases of our proposition.