We chose a JSON-LD format to store our metadata because it is a
recommendation by the World Wide Web Consortium (W3C). Led by Tim
Berners-Lee who invented the World Wide Web, the W3C is a governing
board that proposes standards for the Web such as HTML, XML, CSS, and of
course, JSON-LD. A major push by the W3C is the idea of a “Semantic
Web.” In 2001, Tim Berners-Lee proposed the idea of a Semantic Web in a
sensationalized article published in Scientific American . The
Semantic Web was to be different from the World Wide Web in that it was
to be readable both by humans and machines. The promises of such a Web
were vast. Computers would be able to be agents of themselves, searching
the web in an automated way for whatever information they wanted. In
order to enable this, data would need to be “linked” together in a
massive web. A JSON-LD is a special format of a JSON where these kinds
of linkages are made. The basic objects that exist in a regular json
document are shown in the figure below.
A JSON-LD uses these basic objects and adds a context to them that links ideas together.
The outline that we use to create our JSON-LD files comes from a structure that we create through the formation of an ontology. An ontology is a formal dictionary of terms for a given industry or field that shows how the terms are related through densely interconnected web. Part of the point of doing this is to standardize terms for data by defining how variables should be defined across a given industry. For a photovoltaic system, for example, latitude is to be spelled exactly latitude (not lat, latd, etc), and it is to be measured in degrees. This way, there is no ambiguity. An ontology not only defines terms, but it defines a structure for the metadata as well. An ontology is the blueprint for linking metadata terms together through the creation of a knowledge graph. When an ontology is filled in with real data, it becomes a knowledge graph. For our purposes right now though, the ontology purely exists to provide structure for our metadata. We have designed our ontologies with structures informed by the Basic Formal Ontology (BFO) in order to adhere to standards.
The W3C Web Ontology Language (OWL) is a Semantic Web language designed to represent rich and complex knowledge about things, groups of things, and relations between things. OWL is a computational logic-based language such that knowledge expressed in OWL can be exploited by computer programs, e.g., to verify the consistency of that knowledge or to make implicit knowledge explicit. OWL documents, known as ontologies, can be published in the World Wide Web and may refer to or be referred from other OWL ontologies.  We save our ontologies as .owl files.
We proposed the following naming schema to define file names.
 M. D. Wilkinson, M. Dumontier, I. J. Aalbersberg, G. Appleton, M. Axton, and A. Baak, “The FAIR Guiding Principles for scientific data management and stewardship,” Scientific Data, vol. 3, no. 1, pp.1–9, Mar. 2016
 cT. BERNERS-LEE, J. HENDLER, and O. LASSILA, “THE SEMANTIC WEB,” Scientific American, vol. 284, no. 5, pp. 34–43, 2001.