Similarity between the Xu & Borovsky (2015) solar wind types and the similarity-PAC solar wind categorization for different threshold values. The x-axis varies the value of the threshold on the proton-proton collisional age between coronal hole wind and helmet-streamer plasma , and the y-axis varies threshold values between helmet-streamer and sector-reversal plasma . The similarity of the two categorizations is estimated as the ratio of the number of data points that are categorized as the same solar wind type for both schemes over all valid (non-ICME) data points. The plus indicates the maximum of the similarity measure.