Correlation between the total enrichment in s-process elements and the [hs/ls] index. The objects of this paper are named. The others are the 21 μm sources from Van Winckel & Reyniers (2000), and the two enriched objects from Reyniers et al. (2004). The full line gives the least-squares fit to all data points, the dashed line to all data points except for J053253, and the dotted line, which is given for comparison, to all older data points.