diff --git a/docs/RUGNUX_INTEGRATION.md b/docs/RUGNUX_INTEGRATION.md
index a1dc7cc16..846c6fc2d 100644
--- a/docs/RUGNUX_INTEGRATION.md
+++ b/docs/RUGNUX_INTEGRATION.md
@@ -120,16 +120,21 @@ independently determined orientation matrix agrees with rugnux's to well under a
 The reflection files are inputs to other suites, and the handover has a few conventions worth one
 line each. These are the minimum commands that get each program running on rugnux output.
 
-**phenix.** The merged MTZ carries both `IMEAN` and `I(+)`/`I(-)`, and phenix refuses to choose
-between two equally usable intensity arrays (`Multiple equally suitable arrays of observed xray
-data found`) — name the array, noting that the two programs take different parameter names for the
-same choice:
+**phenix.** The merged files carry both the mean intensity and the Bijvoet pairs, and phenix
+refuses to choose between two equally usable intensity arrays — `Sorry: Multiple equally suitable
+arrays of observed xray data found.` (from the mmCIF the message at least lists the choices; from
+the MTZ it names none, which is where a user is genuinely stuck). It is one behaviour surfacing in
+both formats; only the label vocabulary differs, following each format's own column names — the
+MTZ label fails on the mmCIF with `Sorry: No matching array`:
 
 ```
 phenix.xtriage myrun.mtz xray_data.obs_labels=IMEAN,SIGIMEAN
+phenix.xtriage myrun.cif xray_data.obs_labels=intensity_meas
 phenix.refine  model.pdb myrun.mtz miller_array.labels.name=IMEAN
 ```
 
+(phenix.refine takes a different parameter name for the same choice.)
+
 **The R-free convention.** `FreeR_flag` is **0 = work, 1 = free** (the phenix/CNS convention;
 5 % free by default). phenix.refine detects that on its own. **REFMAC5 does not**: its default
 takes flag 0 as the free set and stops with `Error ==> Cannot switch free R flag` — give it the