diff --git a/doc/manuals/chapters/configuration.adoc b/doc/manuals/chapters/configuration.adoc
index c46a23c..f995bc7 100644
--- a/doc/manuals/chapters/configuration.adoc
+++ b/doc/manuals/chapters/configuration.adoc
@@ -231,6 +231,7 @@
 |pdp-deact|GTP DELETE PDP CONTEXT CONFIRM received from GGSN
 |pdp-terminate|Forced PDP context termination during MM context release
 |pdp-free|Release of the PDP context memory
+|pdp-periodic|Triggered by periodic timer, see VTY cmd _cdr interval_
 |===