Slot value annotations are propositions about individual slot values. For example, imagine that the value of the age slot of Fred is 25. Imagine further that we assign an 80% probability to the correctness of the assertion that the age of Fred is 25, and that the source of our information about Fred's age is Judy. Using logical notation, this information could be expressed as:
age(Fred,25) probability( age(Fred,25) , .8) source( age(Fred,25) , Judy)
Slot value annotations (value annotations for short) allow us to manipulate labeled annotations for particular slot values. For example, we could retrieve the probability of the value 25 of of the age of Fred. In a way, these annotations are like an additional optional layer of own slots within each value -- as if we treated a value as an instance frame. Yet these slots have no inheritance, no value constraints, and no facets. How the underlying FRS implements these annotations is not our concern.
Value annotations are not to be confused with facets, which are annotations for entire slots rather than for individual values.