diff --git a/doc/source/simulation.rst b/doc/source/simulation.rst
index f5a643ff38bed4965c487671e0835863fa55d2ed..842859326ac35f129bdcf2dafdda007b775f7d87 100644
--- a/doc/source/simulation.rst
+++ b/doc/source/simulation.rst
@@ -3,12 +3,13 @@ Using simulation data
 
 Versions
 --------
-In pipeline system, we use ``ver_sim`` keyword in code (e.g., ``CsstMsDataManager``).
-The ``ver_sim`` uses a ``CX.Y`` format string, where
+The current available CSST simulation data products are not versioned.
+Therefore, in pipeline system, we use ``ver_sim`` keyword in code (e.g., ``CsstMsDataManager``).
+The ``ver_sim`` uses a ``C{X}.{Y}`` format string, where
 ``X`` denotes the Cycle during which the simulation is released,
 and ``Y`` denotes the serial number.
 For example, ``C5.2`` represents for the second released version of simulation in Cycle 5.
-s
+
 
 Server details
 --------------
diff --git a/doc/source/unittest.rst b/doc/source/unittest.rst
index 43cca9277b8299888ee68b7ad4a9d80389c891f4..5daf3f346f87337f5b8da042711c088805720386 100644
--- a/doc/source/unittest.rst
+++ b/doc/source/unittest.rst
@@ -7,7 +7,7 @@ And `coverage`_ is used to assess the unit test coverage.
 
 Introduction to ``unittest``
 ----------------------------
-Here we show an example of an example unit test on ``csst_proto.top_level_interface.flip_image``
+Here we show an example unit test on ``csst_proto.top_level_interface.flip_image``.
 
 .. literalinclude:: ../../tests/test_flip_image.py
    :linenos: