diff --git a/README.md b/README.md
index df749f52da7bd0627e929ba9c7071ee9ba362a2b..16964a50103cb81f52eb10b9f07cf721ee125e26 100755
--- a/README.md
+++ b/README.md
@@ -21,6 +21,16 @@ For a given version `X.Y.Z`, the data is stored in the directory `/data/X.Y.Z/`
 - `tables`: CSV tables with attributes derived from image data and segmentations.
 
 
+### Table storage
+
+Derived attributes are stored in csv tables. Tables must be associated with a segmentation file `segmentations/segmentation-name.xml`
+All tables associated with a given segmentation must be stored in the sub-directory `tables/segmentation-name`.
+If this directory exists, it must at least contain the file `default.csv` with spatial attributes of the segmentation objects , which are necessary for the platybrowser table functionality.
+
+TODO think about linking to previous table version. Simplest option would be to replace the directory `tables/segmentation-name` with a
+text file that contains the absolute path to the previous table version.
+
+
 ## Data generation
 
 In addition to the data, the scripts for generating the derived data are also collected here.