## 1 Introduction  
In 2016, and as a part of a doctoral thesis, some of the authors elaborated a catalogue of immovable assets of the Spanish industrial heritage [1]. Despite the main objective of the research work being the design of a methodology based on multi-criteria decision-making tools, previous tasks that were identified included both the need of a wider catalogue of assets and a structure of classification criteria that applied to all of them. At that moment, the Initial Catalogue of the National Plan of Industrial Heritage [2], the Minimum Catalogue of the The International Committee for the Conservation of the Industrial Heritage (TICCIH)-Spain [3], and the catalogue developed by The DOCOMOMO (international committee for DOcupmentation and COnervation of buildings, sites and neighborhoods of the MOdern MOvement) Foundation about the industrial buildings of the modern movement in Spain and Portugal [4], were the main cataloguing initiatives in the country. All of them were of great interest, especially with regard to their different approaches to the problem, but the number of assets that was considered in all of the cases was not large enough to be representative of this typology across the whole national territory. The need to identify and classify the existing assets of value is considered in some of the most recognized documents about protection and actuation regarding the immovable assets of the cultural heritage, such as The Declaration of Amsterdam [5], which is focused on general architectural heritage,and The Nizhny Tagil Charter for the Industrial Heritage, which is specifically focused on this typology [6]. However, traditional cataloguing strategies must be revised and improved, both from a general approach to cultural heritage as well as from particular approaches to specific typologies [7; 8], as the industrial heritage is [9]. Unfortunately, it is not difficult to identify examples of reuse actions above these kinds of assets in which the relation to the productive process has disappeared. These situations reveal that the concept of industrial heritage and the real value of these assets are not yet sufficiently clear. In that sense, some of the widely recognized definitions describe the industrial heritage as the result of the relation between a social model, the capitalism, and the productive resources of the mechanization [2; 3]. This approach involves chronological limits that have been discarded by the authors of this work, who have considered both preindustrial and industrial assets within the catalogue. It is the singularity with regard to aspects such as the technological exclusivity or innovation, the layout and sizing of the productive spaces, the structure or the constructive techniques applied in order to response to the needs of the productive process, or the historical and social role that the activity had in the region, which are the kinds of features that can provide cultural value to these kind of assets [1]. Thus, in the case of industrial heritage, the recording of these assets should enable the understanding of their productive nature from different approaches [10]. In that context, a new catalogue was developed, including 1354 assets that were classified through 54 different criteria. This made it possible to propose a great amount of analyses by combining different criteria in each case. However, some improvement goals have been identified since then. From a general approach to the initial version of the catalogue of assets, it is obvious that although the number of assets that was considered was significantly higher than the sets of elements, including those referred to in the previous catalogues, there are many more assets of interest that were not identified in that initial version. In addition, the national approach of that first experience required careful work regarding the identification and selection of assets, avoiding any kind of focus on particular territories in order to show real trends.