As of July 1,1997, care labels may come with a new feature — symbols or pictures. These symbols will quickly help you determine how to clean your clothes. Through 1998, the care label must include written instructions with the option of using symbols as well. After 1998, either written instructions or symbols must be provided, but not always both.
"SP519 Care Label Symbols," The University of Tennessee Agricultural Extension Service, SP519-10M-7/98 E12-2015-00-063-99, http://trace.tennessee.edu/utk_agexhome/3