Semantic vs. Syntactic Vocabularies

The semantics and syntax of a controlled vocabulary are also important.

Semantics provide meaning to the terms, in a way understandable to a person (e.g., Altitude refers to the vertical position of a flying object).

Syntax is related to the format instructions for storage of values in computers. Syntax might include information on values such as float, real, ASCII or binary (e.g., Altitude data values are measured in feet, F8.6 [here, the F8.6 indicates the form of the numeric value, 8 characters in total with the possibility of 6 after the decimal]).

As noted previously, usage vocabularies (which are a form of controlled vocabulary) provide information on the terminology for using the data values. Thus, a usage vocabulary would include both semantic metadata (e.g., the term ‘latitude’ and the definition of what this term means) and syntactic metadata (e.g., the data value for latitude is F8.6).

A discovery vocabulary (again, this is a form of controlled vocabulary) does not typically contain syntactic metadata. This is because the discovery vocabulary describes collections of usage terms or data values that have meaning to the community. For example, ‘North Atlantic Ocean’ represents a certain grouping of latitude/longitude values; and represents a specific meaning to the oceanographic community. The term ‘North Atlantic Ocean’ has syntax within itself (e.g., capitalization, allowed spaces) but does have syntax associated with the content; because there is no direct content. The term ‘North Atlantic Ocean’ doesn’t explicitly contain values, but rather is a description of a collection of values.

Have a specific question about the semantic or syntactic vocabularies? Ask MMI!