Fig. 6.

The main classes (rectangles) and properties (connections between the rectangles) of the observation and measurement ontology (OBOE) initially developed by Madin et al. (2007), and modified later by Saunders et al. (2011). An observation is made of an entity. The quality of an entity can be represented by a measure. Measures establish a relationship between the characteristics and a measurement standard via a value, and are obtained with a certain precision. Measures are carried out using a protocol in a certain place at a certain time. Observations can have multiple measures. Entities, characteristics and measurement standards constitute entry points for domain‐specific ontologies. The notations ‘1 : 1’ and ‘0 : n’ are called multiplicities: they indicate how many objects within a given class can be linked to objects of another class. For example in the relationship ‘of entity’, an Observation will be linked to only one entity (‘1 : 1’), while an entity could be linked to 0 or to n Observations (‘0 : n’).