Semantic vs. Syntactic Vocabularies
The semantics and syntax of a controlled vocabularyA managed list of terms. In the context of vocabularies, management typically includes careful selection of terms, maintenance of terms over time (i.e. addition, deprecation, modification), and presentation of the vocabulary in an accessible format. Related Guide 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 valuesMetadata values are the content connected to metadata labels in a metadata element. For example, if the metadata label is "date", the metadata value could be "May 13, 2007". Related Guide in computers. Syntax might include information on values such as float, real, ASCIIAmerican Standard Code for Information Interchange 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 vocabulariesThe set of terms used to identify, analyze, or re-use data values in the native form of the data asset. Related Guide (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 metadataData about data. Metadata provides a context for research findings, ideally in a machine-readable format. It enables discovery of data via an electronic interface, and correct use and attribution of findings. Related Guide (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 vocabularyUse of metadata values or vocabularies to find metadata or data sets. Related Guide (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.
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