[Documentation] Further details on custom keywords

[M-casado]

I would like to request more granular documentation regarding the custom keywords for the ontology validation.
There is a description of each custom keyword, but not of the parameters or properties used within each of them. Some seem self explanatory (e.g. include_self) but others could be used in different ways. For example:

• ontologies: is it always in CURIE format? Is there a constraint to which ontologies it accepts (any from OLS, only from OBO...)?
• classes: does the class' prefix have to match one of the given ontologies at the previous attribute? If so, why the need of the first property?
• relations: Wouldn't it always be rdfs:subClassOf? Or does it accept any other rdfs types that could be used (e.g. domain or range) for ontology validation?
• direct: if false does it imply that the child node cannot be a direct descendant of the parent term? Or does it just state that it doesn't need to be a direct one? On the other hand, If true, does it mean it has to be a direct descendant? Or that it can be a direct descendant?
• format: is this a custom keyword related to the ontology validation? Or just a keyword used in the examples for any other reason?

Are there extra keywords that were not used in the examples but can be used within the said custom keywords?

[theisuru]

We will try to improve the documentation for custom keywords. Probably write a wiki entry about this.