docs: add description of generated file by ndn::AppDelayTracer
diff --git a/docs/source/metric.rst b/docs/source/metric.rst
index c1cec1c..02c1eea 100644
--- a/docs/source/metric.rst
+++ b/docs/source/metric.rst
@@ -222,6 +222,31 @@
...
+ Output file format is tab-separated values, with first row specifying names of the columns. Refer to the following table for the description of the columns:
+
+ +-----------------+---------------------------------------------------------------------+
+ | Column | Description |
+ +=================+=====================================================================+
+ | ``Node`` | node id, global unique |
+ +-----------------+---------------------------------------------------------------------+
+ | ``AppId`` | app id, local unique on the node, not global |
+ +-----------------+---------------------------------------------------------------------+
+ | ``SeqNo`` | seq number of the Interest-Data |
+ +-----------------+---------------------------------------------------------------------+
+ | ``Type`` | Type of delay: |
+ | | |
+ | | - ``LastDelay`` means that ``DelayS`` and ``DelayUS`` represent |
+ | | delay between last Interest sent and Data packet received |
+ | | - ``FullDelay`` means that ``DelayS`` and ``DelayUS`` represent |
+ | | delay between first Interest sent and Data packet received |
+ | | (i.e., includes time of Interest retransmissions) |
+ +-----------------+---------------------------------------------------------------------+
+ | ``DelayS`` | delay value, specified in seconds |
+ +-----------------+---------------------------------------------------------------------+
+ | ``DelayUS`` | delay value, specified in microseconds (10^-6) |
+ +-----------------+---------------------------------------------------------------------+
+
+
.. _app delay trace helper example:
Example of application-level trace helper