## 2 Materials and Methods
### DB Management Layer  
The Les Cottes excavation has operated a Microsoft(tm) Access Database as a primary source of data recording over the last twelve years (2006-2018) [24]. Such a database uses a univocal identifier (ID) (Les Cottes database calls this code square ID (SQUID)), automatically assigned by the total station during the recording phase, to distinguish each find and its related data. Different relational tables organise such values for reconstructing the Les Cottes artefacts and, more generally, any archaeological element, e.g., landmarks, sediment samples and strata limits. The present implementation primarily considers five main attributes:  
1. **Identification (ID).** One univocal code unambiguously identifies each archaeological find. It serves as a primary key in the database and corresponds to the same ID, which determines the related 3D model in a tridimensional repository. Therefore, such an ID permits the association of database information with the 3D model's repository data and vice versa.
2. **Position (3D coordinate point(s)).** A local tridimensional reference system (x, y and z) related to a specific spot-mark within Les Cottes describes the position of each point (3D coordinate).
3. **The number of recorded point(s).** The implementation also defines three types of archaeological finds based on the number of points measured on-site: punctual (one point), bipunctual (two points) and multipunctual (more than two points). In the front row, the punctual type corresponds to an artefact for which the overall dimensions are longer than a minimum size (e.g., 2 cm), and whose centroid represents the 3D coordinate. Likewise, the bipunctual type coincides with elongated objects (one axis is twice longer), whose edges are the coordinate points. In the end, the multipunctual type represents composite objects, which own several 3D points that can be linked to describe a volumetric shape.
4. **Stratigraphic unit (US) of provenance.** Archaeologists extract artefacts from stratigraphic units that arrange the sequence of sedimentary depositions into different ranges of chronology and are commonly associated with a distinct cultural tradition (e.g., archaeological industry).
5. **Material.** The production material(s) (e.g., flint, generic rock, bone) can also categorise the find.  
These five attributes can completely describe the 3D model of a find extracted from any excavation, including Les Cottes. Therefore, the current implementation, through an ad hoc C# programme, queries the Les Cottes database to fetch these five attributes and create one comma-separated value (CSV) file for each find. Thus, this strategy allows saving this information in a standardised way and makes any external data compatible with this process.  
It is important to mention that since the Les Cottes Access database is not compatible with Apple(tm) technologies, it underwent a transformation into a corresponding SQLite database (v. 4.3.0) by utilising external procedures, which make it suitable to be completely incorporated into the iPad. Therefore, it is worth noting that the current application entirely includes such an SQLite database.