diff --git a/pySim/filesystem.py b/pySim/filesystem.py
index 1068930..dec521e 100644
--- a/pySim/filesystem.py
+++ b/pySim/filesystem.py
@@ -917,7 +917,13 @@
         return b''.join(chunks)
 
 
+class BerTlvEF(TransparentEF):
+    """BER-TLV EF (Entry File) in the smart card filesystem.
+    A BER-TLV EF is a binary file with a BER (Basic Encoding Rules) TLV structure
 
+    NOTE: We currently don't really support those, this class is simply a wrapper
+    around TransparentEF as a place-holder, so we can already define EFs of BER-TLV
+    type without fully supporting them."""
 
 
 class RuntimeState(object):
diff --git a/pySim/ts_31_103.py b/pySim/ts_31_103.py
index baa4d25..d5641b3 100644
--- a/pySim/ts_31_103.py
+++ b/pySim/ts_31_103.py
@@ -146,12 +146,12 @@
         super().__init__(fid=fid, sfid=sfid, name=name, desc=desc)
 
 # TS 31.103 Section 4.2.18
-class EF_IMSConfigData(TransparentEF):
+class EF_IMSConfigData(BerTlvEF):
     def __init__(self, fid='6ff8', sfid=None, name='EF.IMSConfigData', desc='IMS Configuration Data'):
         super().__init__(fid=fid, sfid=sfid, name=name, desc=desc)
 
 # TS 31.103 Section 4.2.19
-class EF_XCAPConfigData(TransparentEF):
+class EF_XCAPConfigData(BerTlvEF):
     def __init__(self, fid='6ffc', sfid=None, name='EF.XCAPConfigData', desc='XCAP Configuration Data'):
         super().__init__(fid=fid, sfid=sfid, name=name, desc=desc)
 
@@ -161,7 +161,7 @@
         super().__init__(fid=fid, sfid=sfid, name=name, desc=desc)
 
 # TS 31.103 Section 4.2.21
-class EF_MuDMiDConfigData(TransparentEF):
+class EF_MuDMiDConfigData(BerTlvEF):
     def __init__(self, fid='6ffe', sfid=None, name='EF.MuDMiDConfigData',
                  desc='MuD and MiD Configuration Data'):
         super().__init__(fid=fid, sfid=sfid, name=name, desc=desc)