diff --git a/csst/common/data/__init__.py b/csst/common/data/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..6f24a9fa391e3a6dfad7771f8a33b675490afce3
--- /dev/null
+++ b/csst/common/data/__init__.py
@@ -0,0 +1,2 @@
+from .data import CsstData
+from .mscdata import CsstMscData, CsstMscImgData
diff --git a/csst/common/data.py b/csst/common/data/data.py
similarity index 98%
rename from csst/common/data.py
rename to csst/common/data/data.py
index ba604c0e4d7b97fd5c27577a1926aa09dd4465c3..8b314b7fc4d50fa91e8c2a769313955db41487a4 100644
--- a/csst/common/data.py
+++ b/csst/common/data/data.py
@@ -3,7 +3,7 @@ from collections import OrderedDict
 import astropy.io.fits as fits
 from astropy.io.fits import HDUList, PrimaryHDU
 
-from .CsstException import CsstException
+from ..CsstException import CsstException
 
 
 INSTRUMENT_LIST = ["MSC", ]
diff --git a/csst/msc/mscdata.py b/csst/common/data/mscdata.py
similarity index 92%
rename from csst/msc/mscdata.py
rename to csst/common/data/mscdata.py
index 8cdcccd3ab09c1163195e8a95b819fe5010f3ffc..58b88a0a980895d2e4c5d159b9b23385dc5c05d7 100644
--- a/csst/msc/mscdata.py
+++ b/csst/common/data/mscdata.py
@@ -2,7 +2,7 @@ from collections import OrderedDict
 import astropy.io.fits as fits
 from astropy.io.fits import HDUList, PrimaryHDU, ImageHDU
 from astropy.io.fits.header import Header
-from ..common.data import CsstData
+from csst.common.data import CsstData
 
 
 class CsstMscData(CsstData):
@@ -13,12 +13,22 @@ class CsstMscData(CsstData):
         super(CsstData, self).__init__(primaryHDU, imgHDU, **kwargs)
         self._l1hdr_global = primaryHDU.header.copy()
         #         self._l1hdr_global['SIMPLE']  =  'T' #/ conforms to FITS standard
-        #         self._l1hdr_global['NAXIS']  =  0
+        #         self._l1hdr_global['NAXIS']  =  0kkjk
         self._l1data['sci'] = ImageHDU()
         self._l1data['weight'] = ImageHDU()
         self._l1data['flag'] = ImageHDU()
 
     def set_flat(self, flatimg):
+        """
+
+        Parameters
+        ----------
+        flatimg
+
+        Returns
+        -------
+
+        """
         self._auxdata['flat'] = flatimg
 
     def set_bias(self, biasimg):
diff --git a/csst/common/factory.py b/csst/common/factory.py
index c108d2bc843f0663832bd55af583b9c8fe76e6aa..725d2c8fb2b8556daf92de4d42f787c1f701fe24 100644
--- a/csst/common/factory.py
+++ b/csst/common/factory.py
@@ -1,7 +1,7 @@
 from astropy.io import fits
 
-from .data import INSTRUMENT_LIST
-from ..msc.mscdata import CsstMscImgData
+from .data.data import INSTRUMENT_LIST
+from csst.common.data.mscdata import CsstMscImgData
 
 
 class CsstDataFactory: