diff --git a/docs/source/interfaces/Engineering Diffraction.rst b/docs/source/interfaces/Engineering Diffraction.rst
index 484e9d8de101c2ff926b714f1b42f1fc47c13a56..b9b83b4ddee80aea3924fb7a58fd403e7d8e7828 100644
--- a/docs/source/interfaces/Engineering Diffraction.rst	
+++ b/docs/source/interfaces/Engineering Diffraction.rst	
@@ -372,7 +372,6 @@ Peaks:
   peaks. These peaks can be manually written or imported by selecting a
   (*CSV*) file.
 
-
 Output
 ^^^^^^
 
@@ -524,6 +523,13 @@ To do a refinement, take the following steps:
    - You can also click **Refine All** to run refinement on all runs
      loaded into GSAS tab
 
+During the Fit process, :ref:`EnggSaveGSASIIFitResultsToHDF5
+<algm-EnggSaveGSASIIFitResultsToHDF5>` algorithm will be utilised to
+save the fit results, and also the parameters used, as a `hdf5`
+file. There will be one file per run, indexed by bank ID, and the file
+will be found in the **Runs** directory of the user's output
+directory.
+
 You can toggle the fitted peaks on and off with the **Plot Fitted
 Peaks** checkbox, remove runs from the list with the **Remove Run**
 button, and plot the run and fitted peaks to a larger, separate plot
diff --git a/docs/source/release/v3.13.0/diffraction.rst b/docs/source/release/v3.13.0/diffraction.rst
index 0807a5f1565d5382a68535c52dc83c3ba4443c73..cd22ddfb728e23f9fac9e959517dd7d15e3e1568 100644
--- a/docs/source/release/v3.13.0/diffraction.rst
+++ b/docs/source/release/v3.13.0/diffraction.rst
@@ -26,9 +26,13 @@ Engineering Diffraction
     loaded into the tab
 
 - :ref:`GSASIIRefineFitPeaks <algm-GSASIIRefineFitPeaks>` now supports Pawley refinement as well as Rietveld
-- Single peak fitting output is now saved as HDF5 instead of CSV,
-  using :ref:`EnggSaveSinglePeakFitResultsToHDF5
-  <algm-EnggSaveSinglePeakFitResultsToHDF5>`.
+- HDF5 is now the standard format for saving data from the GUI:
+
+  - Single peak fitting output is now saved as HDF5 instead of CSV,
+    using :ref:`EnggSaveSinglePeakFitResultsToHDF5
+    <algm-EnggSaveSinglePeakFitResultsToHDF5>`
+  - Fit results and parameters are saved to HDF5 from the **GSAS
+    Refinement** tab
 
 
 :ref:`Release 3.13.0 <v3.13.0>`