From LOD to LOIN, from Level of Development to Level of Information Requirement Recently, a very important new legislation for the BIM world was what we can briefly define as the transition from the concept of LOD (Level of Detail) to LOIN (Level of Information Need). Why this change? The LOD concept had been introduced in the Anglo-Saxon and American world, and subsequently each country has developed its own operational approach. Depending on the uses of the models – LOD for infrastructure, for restoration, for construction, etc. – it was possible to recognise the fact that there could be a different approach to levels of development according to different needs. This approach has been valid to this day, however, in day-to-day operations, it is often difficult to circumscribe the real needs of clients according to this scale of development. As an indication, the in-depth design or construction study differs according to the component, supplier or construction system adopted: it is not always necessary to extend a specific LOD to a whole model. Hence the need to evolve the concept of LOD towards what has been defined as Information Requirement Levels. The intention now is to improve the quality of information and to ensure greater flexibility and efficiency in the processes. The Information Requirement Levels are based on a framework of two main levels: prerequisites and content. On the requirements side, it is always necessary to consider why a certain degree of in-depth analysis is required, when the information should be produced, who produces that information and, over time, what actually needs to be produced. In terms of content, this refers to geometric information, alphanumeric information and introduces another fundamental aspect that is linked to documentation. And what are the main differences between LOD and LOIN? The structure that is created using the Levels of Information Requirements is less static and also requires a greater willingness to change the working method also on the part of designers and companies, called for a more collaborative approach and dedicated to reducing information waste. Let’s look at its impact when it comes to determining the information needed in a digital model for when it is used as the basis for managing its operation and maintenance.