Apparently there are exceptions to the nonrefundable airline fares. I purchased a nontransferable, nonrefundable, round-trip ticket to Heathrow, London, from Los Angeles from a well-known international airline for $464 which included all taxes. Departure date: May 8. Return: May 24.
In London, I was to join a tour to Yugoslavia. During the latter part of April, the tour operator informed me that due to unsettled conditions in that country, the dates were changed to departure on May 22 with return June 7. I contacted the airline and they changed the travel dates with no objection.