Line 231: AIRS station ID
Station AIRS-ID: <AIRS station ID>
For North-American stations, this line contains the station ID issued by the Alliance of Information and Referral Systems (AIRS)
if such an ID has been issued. If such an ID hasn't been issued, e.g.
for all non-North American stations, this line may be left out. If you
leave out this line, please make sure to decrease the total number of
header lines in line 1 and the number of auxiliary comment lines in line 102 by 1.