diff --git a/core_standard.py b/core_standard.py
index 61e3475..6804044 100644
--- a/core_standard.py
+++ b/core_standard.py
@@ -18,7 +18,12 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 
-    Functions to parse standard response content.
+    Functions to convert human readable to frame encoded data at command
+    building. Conversely at response parsing.
+
+    The same processing function (command name lowered) is used for building
+    the command and for parsing the response. It is necessary to test the
+    parameter object to affect the correspondiong treatment.
 '''
 
 
diff --git a/stid_readers/core.py b/stid_readers/core.py
index 9832985..1f9a3ed 100644
--- a/stid_readers/core.py
+++ b/stid_readers/core.py
@@ -18,7 +18,12 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 
-    Functions to parse reader command response content.
+    Functions to convert human readable to frame encoded data at command
+    building. Conversely at response parsing.
+
+    The same processing function (command name lowered) is used for building
+    the command and for parsing the response. It is necessary to test the
+    parameter object to affect the correspondiong treatment.
 '''