A 9-character expedition ID identifies all expeditions and is given in the form
where “pkid” is the peak ID, “yy” is the last two digits of the year, “s” is the season, and “nn” is the expedition number. The seasons are numbered as 1=spring, 2=summer, 3=autumn, and 4=winter. For example,
is the expedition ID for Chris Bonington’s Annapurna South Face expedition in spring 1970 and
is the Japanese Everest expedition in spring 2013 where Yuchiro Miura summited at the age of 80 (there were a total of 90 expeditions to Everest that season).