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