What do A pos and C pos mean?
The # column is the rank of each listed entry for Arthritis Care and Research — rank 1 means this entry is where Arthritis Care and Research has the most articles or citations. A pos and C pos show the reciprocal: the position of Arthritis Care and Research within that entry's own ranked list, by articles and citations respectively. A low value means Arthritis Care and Research is among the most prominent contributors for that entry.