The concept of definition data is a major step toward consistent data collection and faster data acquisition. Fundamentally we differentiate between simple data on the one hand, reflecting actual facts found on site at a specific position in the tunnel or a defined region on the surface, and definition data on the other hand. The latter in particular facilitate the data entry via predefined picklists, which contain only values that are actually needed. This concept also s a prerequisite for comparable data, since equal things are always given the same name.

The concept of definition data offers the following advantages:

• Comparability of data, because equal things are always given the same name
• graphic representation oft ext values, done by assigning numeric values when defining them, e.g. assigning the values 1, 2 and 3 to the textual options “waek”, “medium”, “strong”, giving the opportunity, to display those values as a chart.
• Graphic representation of numeric values as classified data, done by defining value ranges, allowing a broad overview and comparison , without loosing their original appearance.

Also the structure of the 2DOC project itself is determined via definition data, e.g. definition of project parts, definition of drives, profiles and theme assignements rank among definition data. This also applies to the templates, defining which contents are to be displayed in tunneltapes, 3D models or chartings. Also the type of presentation (colors, hatches, line strength, etc.) is defined by definition data.