you've put the finger on a weak point in reporting crystallographic statistics ;-). The use of Rmerge and Rsym differs wi(l)dely amongst crystallographers. In my opinion, Rsym should be reported for the single crystal internal symmetry R-factor between symmetry-equivalent reflections, whereas Rmerge should be used as the cross-data-set merging R-factor if several data sets are merged together. However, often, you will find Rmerge in place of Rsym in single-crystal statistics tables ...

Best regards,

Dirk.