diff --git a/xray/README.md b/xray/README.md
index 949350c..eed31d3 100644
--- a/xray/README.md
+++ b/xray/README.md
@@ -11,7 +11,7 @@ The idea is an hierarchical structure of modules
 azav.py:  uses pyFAI to convert images into 1d curves
 dataReduction.py: works on the normalization, referencing and averaging.
 
-Both modules uses some common utilities in utils.py including file based storage for persistency and convenience;
+Both modules uses some common utilities in utils.py including file based storage for persistency and convenience (numpy or hdf5 based);
 Indeed the data_storage class wraps around dictionaries allowing accessing with .attribute syntax.
 In utils plotfuncitons are presents