Next we show a list of rules to obtain a ontology highly readable by humans:

1. Number of names: each element in the ontology (i.e. classes and properties) is expected to have one standardized canonical name consisting in a comprehensive textual representation easy to understand by users from multiple backgrounds.
2. Naming style: the canonical name must follow a systematic naming convention that defines the concept as much as possible. As an example, from the class name 'juvenile osteochondrosis of foot' it can be inferred that it is a type of osteochondrosis located in the foot and that affects young people.
3. Lexically suggest, logically define: the information that can be inferred from the name must be formalized as logical axioms in the ontology. In other words, the human readable content and the machine readable content should be aligned. For example, the class 'juvenile osteochondrosis of foot' should be semantically related to the 'osteochondrosis' and 'foot' ontology classes, if these exist.
4. Number of descriptions: each element in the ontology should have one description. Descriptions are more informative than a simple name, being possible that a name could lead to misunderstandings due to polysemy.
5. Number of synonyms: each element in the ontology must be enriched with synonyms whenever possible. Synonyms are alternative names to the canonical one, which are widely accepted by the community and used in particular domains. This facilitates the understanding by human users from different backgrounds and improves the use of the ontology for NLP processes.
6. The previous rules should be adaptated in case of multilingual ontologies In this case, each element in the ontology should have several names, descriptions and synonyms covering all the languages supported by the ontology.

The metrics provided by HURON, described here, are able to measure the degree in which an ontology meet these rules. The following table shows the association between best practices and metrics:

Ontology element	Best practice	Metric	Optimal value
Classes	Number of names	Names per class	1
	Naming style	Systematic naming	1
	Lexically suggest, logically define	LSLD	1
	Number of descriptions	Descriptions per class	1
	Number of synonyms	Synonyms per class	1
Object Properties	Number of names	Names per object property	1
	Number of descriptions	Descriptions per object property	1
	Number of synonyms	Synonyms per object property	1
Data Properties	Number of names	Names per data property	1
	Number of descriptions	Descriptions per data property	1
	Number of synonyms	Synonyms per data property	1
Annotation Properties	Number of names	Names per annotation property	1
	Number of descriptions	Descriptions per annotation property	1
	Number of synonyms	Synonyms per annotation property	1