What is the relation between Schema.org, Goodrelations-vocabulary.org and Productontology.org?
Schema.org informs, "W3C schema.org Community Group is the main forum for the project". Google, Microsoft, Yahoo and Yandex are founding companies.
Are Google, Microsoft, Yahoo and Yandex accepting Goodrelations-vocabulary.org and Productontology.org standard as well? If not, is it good idea to use them for future?
Although Google did not mention, I read that there are some differences regarding Google approach to structured data.
Schema.org offers Microdata, Google offers application/ld+json etc.
It is not possible to say Google suits to 100 % Schema.org. Is it same for Microsoft, Yahoo and Yandex.
There is no structured way to publish "Yacht Charter" at Schema.org, only way is http://www.productontology.org/doc/Yacht_charter, but this is not offical (till today 13.03.2018).
What is the best way to publish structured data for yacht charter industry?
Do we have to use Offer, AggregateOffer or http://www.productontology.org/doc/Yacht_charter?
Vocabularies
Schema.org defines properties and types primarily for web/email content.
GoodRelations defines properties and types primarily for e-commerce.
The Product Types Ontology defines types (no properties) for every main thing described by an English Wikipedia article.
(Note that Schema.org integrated many parts of GoodRelations: Good Relations and Schema.org.)
Of course there are many more vocabularies, and you could create your own, too.
Syntaxes
All these vocabularies are RDF-based, so they can be used in any RDF serialization (like JSON-LD, RDFa, RDF/XML, Turtle etc.).
They could also be used in Microdata, although it’s not a RDF serialization (but close enough).
Authors and consumers
An author of the structured data decides which vocabularies and which syntaxes to use.
Examples:
The author Stack Overflow uses two vocabularies (Open Graph Protocol, Schema.org) and two syntaxes (Microdata, RDFa) on a Q&A page.
The author Tim Berners-Lee uses 14 vocabularies (Creative Commons, FOAF, DOAP, Solid, Geo, etc.) and one syntax (RDF/XML) in his card.
A consumer (a browser add-on, a stand-alone tool, a web application/service etc.) of the structured data decides which vocabularies and which syntaxes to support.
Examples:
The consumer Google Search supports one vocabulary (Schema.org) and three syntaxes (JSON-LD, Microdata, RDFa) for their rich results.
The consumer Gmail supports one vocabulary (Schema.org) and two syntaxes (JSON-LD, Microdata) for their Gmail Actions/Highlights.
The consumer Facebook supports one vocabulary (Open Graph Protocol) and one syntax (RDFa) for their share feature.
My recommendation for starting
Use the vocabulary Schema.org for everything. It’s the most used vocabulary, it’s supported/sponsored by the big search engine services, and it’s intended for all kind of content.
Use other vocabularies in addition to the types/properties from Schema.org. Schema.org doesn’t cover all areas/domains in depth. Where it is lacking, use suitable, more specific vocabularies.
Use one of these syntaxes: JSON-LD, Microdata, RDFa. See my answer about differences between JSON-LD, Microdata, and RDFa and my answer comparing Microdata and RDFa. Unless you already know one of these syntaxes, I would recommend to go with RDFa (JSON-LD can be easily generated automatically from a HTML+RDFa document, but not the other way around).
So if you provide a yacht charter service, you could use something like this:
<section typeof="schema:Service http://www.productontology.org/id/Yacht_charter">
<h2 property="schema:name">Yacht charter</h2>
</section>
It uses the Service type from Schema.org (none of its more specific types apply to a yacht charter service, so this is as specific as Schema.org currently gets), and the Yacht_charter type from the Product Types Ontology.
