How are co-authors sorted?
Co-authors are ranked by their own lifetime peer-reviewed citation count, not by the number of joint papers with Richard H Rand. A frequent collaborator with modest citation impact may rank below a highly cited collaborator with fewer shared publications.
What do A pos and C pos mean?
The # column is the rank of each listed entry for Richard H Rand — rank 1 means this entry is where Richard H Rand has the most articles or citations. A pos and C pos show the reciprocal: the position of Richard H Rand within that entry's own ranked list, by articles and citations respectively. A low value means Richard H Rand is among the most prominent contributors for that entry.