From Linked Earth Wiki
Category: Observation (L) 
The class ssn:Observation provides the structure to represent a single observation. An observation is a situation that describes an observed feature, an observed property, a sensor and method of sensing used and a value observed for the property: that is, an observation describes a single value attributed to a single property by a particular sensor. Observations of multiple features or multiple properties of the one feature should be represented as either compound properties, features and values or as multiple observations, grouped in some appropriate structure.
This category has only the following subcategory.