Arranges the species entries according to species associated field entries. Up to three fields can be specified in a hierarchical order (1st sort key = dominant sort criterion, ...).
The arrangement is done in the alphabetical or numerical order of the field entries (see WARNINGS below).
Check 'Reverse' below a field selection box to reverse the sort criterion (i.e. sort from big to small).
Missing fields are ALWAYS sorted behind existing fields, then they'll be sorted by the next sort criterion.