# Reshaping the Digital Twin Construct with Levels of Digital Twinning (LoDT)
## 2 Functional Architecture of Digital Twinning  
### Terms and Definitions  
Previous research has been dedicated to both reviewing the knowledge on DTs and seeking a harmonised definition that could be adopted by peers in future works. Despite the succession of such endeavours, a systemic difficulty in adopting these contributions and interpreting the concept of DTs in a harmonised manner seems to persist. In general, interpretations about DTs vary from the more purist, i.e., those closer to the original definitions and interpretations of digital twins, to the more comprehensive ones, which encompass not only what the former define as DTs but also the so-called digital models and digital shadows, for instance. These differences have been identified in literature reviews, such as those by [PERSON] et al. [6] and [PERSON] et al. [10]. Although each author may have their own perspective on the subject and have a specific conceptual position within the spectrum of interpretations mentioned earlier, this article aims to focus on the structural elements that are broadly shared across various interpretations of DTs. In practice, each of these structural elements exhibits its own spectrum of variability. This variability is defined based on several factors, such as the objectives of a DT, the context (both internal and external), and the available resources, among others. This set of elements constructs the comprehensive concept of digital twinning. The term \"digital twinning\" was implicitly introduced by [PERSON] in 2002 when he presented the first model of a \"digital twin\" [19]. The term was explicitly used in 2005 in a UNESCO report titled \"Towards Knowledge Societies\" within the context of digital partnerships between local governments. Currently, the term is sometimes narrowly associated with the collection of point clouds of physical objects (e.g., [20; 21]). This article does not adopt that perspective and favours a more comprehensive concept of digital twinning. This work embraces an interpretation shared by several authors [22; 23; 24], which presents digital twinning as the process of replicating physical objects and processes through digital technologies. The perspective of digital twinning offers the advantage of harmonizing discussions about what truly constitutes a DT by emphasizing that mirroring physical assets into the digital world can manifest in multiple dimensions. Furthermore, the concept of digital twinning does not dismiss the various and sometimes conflicting interpretations found in the literature. Instead, it establishes a shared understanding, enabling both authors and organizations to position themselves within the diverse levels of digital twinning. This can be particularly beneficial given the general lack of understanding among many organizations regarding the capabilities and functioning of DTs, as previously discussed. According to [PERSON] and [PERSON] [25], even though DTs hold significant value generation potential for organisations, their use may not be necessary for all physical assets. This is because not all assets and their respective uses require intensive and automatic data flows, and, therefore, their use may not be financially viable. Therefore, the primary objective of digital twinning should not be to achieve a specific level of development but rather to serve the purpose and meet the needs of asset management in the most effective and efficient manner possible. In other words, digital twinning should seek to generate the highest possible value for the organisation and its stakeholders from the opportunities offered by digital transformation. According to the Gemini Principles (Figure 1), proposed by the Centre for Digital Built Britain [26], DTs must have a clear purpose, be trustworthy, and function effectively. As with asset management, digital twinning should also follow a set of fundamental principles. In asset management, value, alignment, leadership, and assurance are the so-called fundamental elements.