Semantic vs. Syntactic Vocabularies

Semantics is the meaning of words. Semantic vocabularies provide meaning to the terms used in metadata in a way that is understandable to a human being. For example, the semantic vocabulary description for altitude might be, "the vertical position of a flying object."

Syntax in metadata refers to the format instructions for storage of values in computers. Syntax might include information on values such as float, real, ASCII or binary. For example, an entry in a syntactic vocabulary might be, "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 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).

However, a discovery vocabulary typically does not contain syntactic metadata. This is because the discovery vocabulary describes collections of usage terms or data values that already are known to the community.

For example, North Atlantic Ocean represents a certain grouping of latitude and longitude values and represents a specific meaning to the oceanographic community. The term North Atlantic Ocean has inherent syntax (e.g., capitalization and allowed spaces) but does not have syntax associated with the content because the term doesn’t explicitly contain values but rather is a generalized description of a collection of values.

Suggested Citation

Isenor, A. 2011. "Semantic vs. Syntactic Vocabularies." In The MMI Guides: Navigating the World of Marine Metadata. Accessed July 16, 2020.