rtaxref queries the API of the French Taxonomic Referential (TAXREF). This referential contains much taxonomical information as well as many other kinds of information (occurrence in French territories, conservation statuses, etc.).
TODO explain rt_taxa_search().
Talk about importance of id of species (CD_NOM).
Refer to the documentation of function to get lists of values of potential arguments.
Querying a specific version of TAXREF.
Vernacular names, history of taxon in TAXREF, uses
externals ids and related databases.