External Terms

An external term is a term in a published vocabulary governed by someone else, named by the identifier that vocabulary gives it: what a locally governed term can be said to correspond to, so a comparison is possible without either vocabulary taking the other over.

Its external terms— 3

• schema.org FAQPageThe class schema.org publishes for a page of questions and answers, defined there as a web page presenting one or more frequently asked questions.
• schema.org BlogPostingThe class schema.org publishes for a blog post, defined there in those words and placed under its article class.
• schema.org HowToThe class schema.org publishes for step-by-step instructions, defined there as instructions that explain how to achieve a result by performing a sequence of steps.

Why it matters

What goes wrong without it, as the commitments that license this kind say it, each standing on its sources.

• A correspondence to a vocabulary governed elsewhere is asserted, never importedAdopting an industry vocabulary as the master buys comparability and hands over governance of the words: when the external scheme revises, local meanings move with it, and a term that carried a specific operational sense is reinterpreted by a committee somewhere else. Refusing it altogether buys the opposite problem, because the systems a practitioner actually runs are keyed on those schemes, and a vocabulary that cannot say what it corresponds to can only be read, never joined. A mapping is the arrangement that keeps both, and the knowledge-organization standards have held it as its own set of statements for exactly this reason rather than as a property of either side. Asserting it as a relationship to a term of the other vocabulary, rather than as a field on a term of this one, is what keeps the two vocabularies separable: the correspondence can be withdrawn without touching either, and a reader can see whose term is whose. The evidence bar is high on purpose, because a correspondence asserted loosely is a false public claim about someone else's words, and a practitioner who trusts it keys a system on it.
  SKOS Simple Knowledge Organization System Reference · ISO 25964-2 Information and documentation, Thesauri and interoperability with other vocabularies, Part 2: Interoperability with other vocabularies · ISO 25964-1:2011 Information and documentation, Thesauri and interoperability with other vocabularies, Part 1: Thesauri for information retrieval