Real world article
(written from a production point of view)
Referenced in the writers' first draft script of the Star Trek: Enterprise first season episode "Dear Doctor", Iyax was an area on the planet Denobula. With the locale having presumably been mentioned by Doctor Lucas in a letter he sent Dr. Phlox, Phlox replied in a letter of his own, "You're right, the temperature in Iyax is frigid this time of year," then proceeded to suggest that Lucas take a circulation enhancer to resist the cold and implied that the climate of Iyax was why he himself had never had complained about the weather in San Francisco. Phlox ended the letter by saying, "My regards to Iyax and the homeworld."