## 1 Introduction  
In the last decade, there has been a revolution within the construction sector that aims to the digitization of the entire building process. At the base of this dynamic, there is the increasing demand for the formulation of a Building Information Model. This design and management tool of the building system sees a deep-rooted presence in some states, although its methods of use are constantly evolving. The United Kingdom, Germany and countries of Northern Europe are among the front-line players in the adoption of this system. Their work has led to the formulation of national standards for the realization of these 3D models: such as the English BS EN ISO 19650 of 2018 that was born from the homonymous ISO standard and replaces the previous BS 1192 and PAS 1192 [1; 2; 3; 4; 5; 6; 7].  
According to Ministerial Decree 560/17 [8], a similar change will be necessary also in the Italian context, imposing BIM as the instrument behind any intervention, both newly built and on the existing one. However, the success of this purpose requires an important process of regulation. Thinking of the Italian context and the heterogeneity of the elements that compose its urban fabric, structured regulatory instruments are indispensable. These allow an agile use of BIM in all conditions and also in the case of HBIM. Standards, on the one hand, must have a close reference to international regulations. On the other hand, they must demonstrate maximum flexibility and interoperability with regard, in particular, to the modeling of existing historic buildings.  
A first reflection could be on the principles underlying modeling and its digital tools. It is necessary to assume that BIM software was thought for new buildings, but now it is trying to expand its use also for existing ones, such as architectural cultural heritage and historic buildings in general. With these premises, it is essential to review the approach behind the modeling. Paradoxically, for such objects, the spread of this system is leading us to think that it is not possible to talk about predefined and regular geometries. It is necessary to prepare a tool that can be adapted to all foundable cases. The current software (e.g., Autodesk Revit) and their modeling tools struggle to work with particular and unique architectural objects, which can be detected in any historical building.  
A second important topic is the language, specifically related to classification and nomenclature of the objects. To provide a method, it is also essential to offer a language and an encoding model of everything contained in the BIM model. It must be easily implementable and a general, flexible, and universally understandable vocabulary. This need is the basis for strong interoperability and the dissemination of the instrument. In parallel with English legislation, standardization of language based on UNI 8290 and the relative building system breakdown could be hypothesized. With this premise, the proposal for a structure that refers to the GIS (Geographic Information System) world--specifically to the CISIS Topographic Database--and its succession \"layer-theme-class\" was born [9]. All this was with the aim of language standardization and solid interoperability between different entities, a fundamental concept of the BIM world and the various software that are part of it.  
This text addresses both of these topics. It tries to analyze them and formulates possible solutions. The work deals with these issues following an HBIM modeling experience, which has raised questions about software standards and software difficulties. The aim is to propose a reflection on these themes and consequent solutions as articulating a new BIM tool and a common language aimed at the classification and nomenclature of moldable objects.