# Reshaping the Digital Twin Construct with Levels of Digital Twinning (LoDT)
## 4 Assessing the Level of Digital Twinning (LoDT)  
As previously discussed, the digital twinning of physical assets unfolds in several dimensions, each of which may exhibit different degrees of complexity, requiring alignment with the pre-defined purpose. Therefore, the digital twinning of physical assets is an ongoing evolutionary process [63], albeit limited by its own scope, context, and application purpose. \begin{table}
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Some authors have attempted to demonstrate the existence of different maturity levels of DTs through models of variable complexity and scope. For instance, [PERSON] et al. [45] focused solely on classifying differences in terms of connectivity. The International Data Corporation maturity model [64] addressed the perspective of collaboration within DTs. On the other hand, the models proposed by Digital Government Authority [65], TechUK [66], and [PERSON] [67] sought to distinguish the hierarchical levels of DTs. Other authors such as [PERSON] et al. [68], CDBB [69], [PERSON] et al. [70], [PERSON] [71], and BSI [72] focused on classification models with generic levels of DT. Furthermore, authors like ARUP [73], IoT Analytics [7], [PERSON] and [PERSON] [74], [PERSON] et al. [75], [PERSON] and [PERSON] [76], [PERSON] et al. [77], and [PERSON] et al. [63] identified specific dimensions in which the concept of DT may exhibit variability. Nevertheless, these proposals were often unclear regarding the distinctions between certain dimensions, incomplete, or overly detailed for an implementation that aims to be accessible and clear for most organisations. Therefore, the authors of this study aim to harmonise the functioning of the proposed architecture with existing evaluation models into a unified assessment tool. This assessment model of digital twinning levels--entitled UNI-TWIN--seeks to support digital twinning strategies within organisations through a continuous process of evaluating the current situation, comparing it with other contexts (internal or external), and identifying potential development opportunities [63]. UNI-TWIN is not a maturity assessment model, wherein higher levels of digital twinning do not necessarily imply greater maturity. Conversely, relatively simple models in terms of digital twinning complexity may exhibit a higher level of maturity in some applications. Indeed, as specified in ISO 19650-2, an increase in detail can lead to waste, which should be avoided by carefully specifying and complying with information requirements [78]. Rather than assessing maturity, the UNI-TWIN model provides a comprehensive representation of the complexity in current or possible scenarios based on the dimensions that constitute the overarching concept of digital twinning. The LoDT proposed in this paper shares common aspects with the Level of Information Need from the field of BIM. Since the publication of PAS 1192-2:2013, there has been a transition in requirement specification from a Level of Development (LOD) to a Level of Information Need. The evolution of BIM standards from a more prescriptive approach to one in which the requirements of the appointing party dictate the level of information requested [79; 80] has taken decades and has required increasing maturity from the entities involved in the contracting processes, as well as the development of a broader regulatory context (including standards for models and for information management processes). As discussion continues in the field of BIM regarding the different levels of geometrical and non-geometrical requirements, still with a major focus on construction projects, there is a need to look outside the design and construction phases of physical assets and discuss if the existing requirement structure is sufficient to cover the broad concept of digital twinning.