diff --git a/Code/Mantid/docs/source/algorithms/CatalogDownloadDataFiles-v1.rst b/Code/Mantid/docs/source/algorithms/CatalogDownloadDataFiles-v1.rst
index d00809997b6ab555d213f51372c4d71ef2d77f4b..3f21115aeb30c9d2e1c5136302e28b0b6b6cacc1 100644
--- a/Code/Mantid/docs/source/algorithms/CatalogDownloadDataFiles-v1.rst
+++ b/Code/Mantid/docs/source/algorithms/CatalogDownloadDataFiles-v1.rst
@@ -46,7 +46,11 @@ Output:
 
     # This option will not append any file extensions to the datafiles.
     CatalogDownloadDataFiles(FileIds = datafile_ids,    # We now pass our list of ids here
-                             FileNames = datafile_ids,  # and also here.
+                             # The filenames are those that will be saved on your machine
+                             # I have opted to use the datafile ids for this, but it is possible
+                             # to provide a list of desired names.
+                             # This must be the same size as the FileIds list.
+                             FileNames = datafile_ids,
                              DownloadPath = '~/Desktop',
                              Session = session.getPropertyValue("Session")
                              )