diff --git a/csst_common/__init__.py b/csst_common/__init__.py
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..03b4017a109f9111732253bc1623d4cba939e777 100644
--- a/csst_common/__init__.py
+++ b/csst_common/__init__.py
@@ -0,0 +1,5 @@
+import os
+
+__version__ = "0.0.1"
+
+PACKAGE_PATH = os.path.dirname(__file__)
diff --git a/csst_common/params.py b/csst_common/params.py
index 5bce9ac5f54323a37d4b294e809579935d63cca9..86fbd9ce0985989d1f7fb31e91c4bd4bc146aa00 100644
--- a/csst_common/params.py
+++ b/csst_common/params.py
@@ -3,9 +3,10 @@ class BasicParams:
     """ the basic parameter class """
     def __repr__(self):
         _class_name = self.__class__.__name__
-        _str = "<{}>\n{}\n".format(_class_name, "-" * (len(_class_name) + 2))
+        _str = "<{} length={}>".format(_class_name, len(self.__dict__))
+        _str += "\n{}\n".format("-" * len(_str))
         for k, v in self.__dict__.items():
-            _str += "{}:{} \n".format(k, v)
+            _str += "{} : {} \n".format(k, v)
         return _str
 
     # def to_dict(self):
@@ -20,13 +21,26 @@ class BasicParams:
 class CsstParams(BasicParams):
     """ CSST parameters -- a collection of """
     def __init__(self):
+        """
+        This class defines the CSST parameters.
+
+        Example
+        -------
+        >>> from csst_common.params import CsstParams
+        >>> cps = CsstParams()
+
+        See also
+        --------
+        CsstMbiParams, CsstSlsParams, CsstSimParams
+        """
         self.mbi = CsstMbiParams()
         self.sls = CsstSlsParams()
         self.sim = CsstSimParams()
 
     def __repr__(self):
         _class_name = self.__class__.__name__
-        _str = "<{}>\n{}\n".format(_class_name, "-"*(len(_class_name)+2))
+        _str = "<{} length={}>".format(_class_name, len(self.__dict__))
+        _str += "\n{}\n".format("-" * len(_str))
         for k, v in self.__dict__.items():
             _str += "{}: \n".format(k)
             for kk in self.__getattribute__(k).__dict__.keys():
@@ -79,6 +93,8 @@ class CsstSimParams(BasicParams):
         self.VER_SIMS = ["C3", "C5.1", "C5.2"]
 
 
+cp = CsstParams()
+
 if __name__ == "__main__":
     cp = CsstParams()
     print(cp)