Resolution No.4 (1983): Scaling technique of K by hand and by machine

IAGA recognising that the quality of results from long time series depends on the accuracy and homogeneity of the data sets; notes that K indices from different networks of observatories have been used for many years in deriving planetary activity indices Ap, Am and Aa, and that some observatories are now using digital recording systems and machine data reductions; and recommends

1. that routine derivation of K-indices continues by hand scaling according to the method proposed by Bartels (developed by Mayaud in IAGA Bulletin No. 21); and
2. that new machine derived indices be given distinctly different names to avoid confusion with existing indices.