taxonID (http://rs.tdwg.org/dwc/terms/taxonID) @return [String] The unique identifier used for a name or taxon reference in the core data file. Each row in the core data file has a unique taxonID and it should be the first column in the data file. Synonyms occupy separate lines and therefore also have unique taxonIDs. TaxonIDs may be simple integers or more complex globally unique identifiers. Examples: 101; “8fa58e08-08de-4ac1-b69c-1235340b7001;