diff --git a/owslib/catalogue/csw2.py b/owslib/catalogue/csw2.py
index e09555b7..193d831e 100644
--- a/owslib/catalogue/csw2.py
+++ b/owslib/catalogue/csw2.py
@@ -20,8 +20,8 @@
 from owslib import util
 from owslib import ows
 from owslib.iso import MD_Metadata, FC_FeatureCatalogue
-from owslib.iso_3 import MD_Metadata as MD_Metadata_3  # ISO 19115 Part 3 XML
-from owslib.iso_3 import FC_FeatureCatalogue as FC_FeatureCatalogue_3  # ISO 19115 Part 3 XML
+from owslib.iso3 import MD_Metadata as MD_Metadata3  # ISO 19115 Part 3 XML
+from owslib.iso3 import FC_FeatureCatalogue as FC_FeatureCatalogue3  # ISO 19115 Part 3 XML
 from owslib.fgdc import Metadata
 from owslib.dif import DIF
 from owslib.gm03 import GM03
@@ -580,12 +580,12 @@ def _parserecords(self, outputschema, esn):
                 val = i.find(util.nspath_eval('gm03:fileIdentifier', namespaces))
                 identifier = self._setidentifierkey(util.testXMLValue(val))
                 self.records[identifier] = GM03(i)
-        elif MD_Metadata_3.handles(outputschema):  # ISO 19115 Part 3 XML
-            for elem, id in MD_Metadata_3.find_ids(self._exml):
-                self.records[self._setidentifierkey(id)] = MD_Metadata_3(elem)
+        elif MD_Metadata3.handles(outputschema):  # ISO 19115 Part 3 XML
+            for elem, id in MD_Metadata3.find_ids(self._exml):
+                self.records[self._setidentifierkey(id)] = MD_Metadata3(elem)
             for i in self._exml.findall('.//' + util.nspath_eval('gfc:FC_FeatureCatalogue', namespaces)):
                 identifier = self._setidentifierkey(util.testXMLValue(i.attrib['uuid'], attrib=True))
-                self.records[identifier] = FC_FeatureCatalogue_3(i)
+                self.records[identifier] = FC_FeatureCatalogue3(i)
         else:  # process default
             for i in self._exml.findall('.//' + util.nspath_eval('csw:%s' % self._setesnel(esn), namespaces)):
                 val = i.find(util.nspath_eval('dc:identifier', namespaces))
diff --git a/owslib/catalogue/csw3.py b/owslib/catalogue/csw3.py
index 77dbc36e..64e9ea58 100644
--- a/owslib/catalogue/csw3.py
+++ b/owslib/catalogue/csw3.py
@@ -20,8 +20,8 @@
 from owslib import util
 from owslib import ows
 from owslib.iso import MD_Metadata, FC_FeatureCatalogue
-from owslib.iso_3 import MD_Metadata as MD_Metadata_3  # ISO 19115 Part 3 XML
-from owslib.iso_3 import FC_FeatureCatalogue as FC_FeatureCatalogue_3  # ISO 19115 Part 3 XML
+from owslib.iso3 import MD_Metadata as MD_Metadata3  # ISO 19115 Part 3 XML
+from owslib.iso3 import FC_FeatureCatalogue as FC_FeatureCatalogue3  # ISO 19115 Part 3 XML
 from owslib.fgdc import Metadata
 from owslib.dif import DIF
 from owslib.gm03 import GM03
@@ -479,12 +479,12 @@ def _parserecords(self, outputschema, esn):
                 val = i.find(util.nspath_eval('gm03:fileIdentifier', namespaces))
                 identifier = self._setidentifierkey(util.testXMLValue(val))
                 self.records[identifier] = GM03(i)
-        elif MD_Metadata_3.handles(outputschema):  # ISO 19115 Part 3 XML
-            for elem, id in MD_Metadata_3.find_ids(self._exml):
-                self.records[self._setidentifierkey(id)] = MD_Metadata_3(elem)
+        elif MD_Metadata3.handles(outputschema):  # ISO 19115 Part 3 XML
+            for elem, id in MD_Metadata3.find_ids(self._exml):
+                self.records[self._setidentifierkey(id)] = MD_Metadata3(elem)
             for i in self._exml.findall('.//' + util.nspath_eval('gfc:FC_FeatureCatalogue', namespaces)):
                 identifier = self._setidentifierkey(util.testXMLValue(i.attrib['uuid'], attrib=True))
-                self.records[identifier] = FC_FeatureCatalogue_3(i)
+                self.records[identifier] = FC_FeatureCatalogue3(i)
         else:  # process default
             for i in self._exml.findall('.//' + util.nspath_eval('csw30:%s' % self._setesnel(esn), namespaces)):
                 val = i.find(util.nspath_eval('dc:identifier', namespaces))
diff --git a/owslib/feature/wfs100.py b/owslib/feature/wfs100.py
index 11d181c1..0484affd 100644
--- a/owslib/feature/wfs100.py
+++ b/owslib/feature/wfs100.py
@@ -25,7 +25,7 @@
 from owslib.etree import etree
 from owslib.fgdc import Metadata
 from owslib.iso import MD_Metadata
-from owslib.iso_3 import MD_Metadata as MD_Metadata_3  # ISO 19115 Part 3 XML
+from owslib.iso3 import MD_Metadata as MD_Metadata3  # ISO 19115 Part 3 XML
 from owslib.crs import Crs
 from owslib.namespaces import Namespaces
 from owslib.feature.schema import get_schema
@@ -471,9 +471,9 @@ def parse_remote_metadata(self, timeout=30):
                         if mdelem is not None:
                             metadataUrl["metadata"] = MD_Metadata(mdelem)
                         else:
-                            mdelem = MD_Metadata_3.find_start(doc)
+                            mdelem = MD_Metadata3.find_start(doc)
                             if mdelem is not None:
-                                metadataUrl["metadata"] = MD_Metadata_3(mdelem)
+                                metadataUrl["metadata"] = MD_Metadata3(mdelem)
                             else:
                                 metadataUrl["metadata"] = None
                 except Exception:
diff --git a/owslib/feature/wfs110.py b/owslib/feature/wfs110.py
index 0977cf75..ab28e922 100644
--- a/owslib/feature/wfs110.py
+++ b/owslib/feature/wfs110.py
@@ -18,7 +18,7 @@
 from owslib.etree import etree
 from owslib.fgdc import Metadata
 from owslib.iso import MD_Metadata
-from owslib.iso_3 import MD_Metadata as MD_Metadata_3  # ISO 19115 Part 3 XML
+from owslib.iso3 import MD_Metadata as MD_Metadata3  # ISO 19115 Part 3 XML
 from owslib.ows import (
     OwsCommon,
     ServiceIdentification,
@@ -488,9 +488,9 @@ def parse_remote_metadata(self, timeout=30):
                         if mdelem is not None:
                             metadataUrl["metadata"] = MD_Metadata(mdelem)
                         else:
-                            mdelem = MD_Metadata_3.find_start(doc)
+                            mdelem = MD_Metadata3.find_start(doc)
                             if mdelem is not None:
-                                metadataUrl["metadata"] = MD_Metadata_3(mdelem)
+                                metadataUrl["metadata"] = MD_Metadata3(mdelem)
                             else:
                                 metadataUrl["metadata"] = None
                 except Exception:
diff --git a/owslib/feature/wfs200.py b/owslib/feature/wfs200.py
index 4e731fa2..296548b0 100644
--- a/owslib/feature/wfs200.py
+++ b/owslib/feature/wfs200.py
@@ -10,7 +10,7 @@
 from owslib import util
 from owslib.fgdc import Metadata
 from owslib.iso import MD_Metadata
-from owslib.iso_3 import MD_Metadata as MD_Metadata_3  # ISO 19115 Part 3 XML
+from owslib.iso3 import MD_Metadata as MD_Metadata3  # ISO 19115 Part 3 XML
 from owslib.ows import Constraint, ServiceIdentification, ServiceProvider, OperationsMetadata
 from owslib.etree import etree
 from owslib.util import nspath, testXMLValue, openURL, Authentication
@@ -613,9 +613,9 @@ def parse_remote_metadata(self, timeout=30):
                         metadataUrl["metadata"] = MD_Metadata(mdelem)
                         continue
                     else:  # ISO 19115 Part 3 XML
-                        mdelem = MD_Metadata_3.find_start(doc)
+                        mdelem = MD_Metadata3.find_start(doc)
                         if mdelem is not None:
-                            metadataUrl["metadata"] = MD_Metadata_3(mdelem)
+                            metadataUrl["metadata"] = MD_Metadata3(mdelem)
                         else:
                             metadataUrl["metadata"] = None
                         continue
diff --git a/owslib/iso_3.py b/owslib/iso3.py
old mode 100755
new mode 100644
similarity index 99%
rename from owslib/iso_3.py
rename to owslib/iso3.py
index 43770d46..4e3689d8
--- a/owslib/iso_3.py
+++ b/owslib/iso3.py
@@ -14,7 +14,7 @@
     Parsing is initiated by passing in etree root Element to the 'MD_Metadata' constructor:
 
     from owslib.etree import etree
-    from owslib.iso_3 import MD_Metadata
+    from owslib.iso3 import MD_Metadata
 
     exml = etree.fromstring(xml_bytes)
     mdb = MD_Metadata(exml)
diff --git a/owslib/map/wms111.py b/owslib/map/wms111.py
index 99cf11f8..ab4b795d 100644
--- a/owslib/map/wms111.py
+++ b/owslib/map/wms111.py
@@ -25,7 +25,7 @@
                          bind_url, nspath_eval, Authentication)
 from owslib.fgdc import Metadata
 from owslib.iso import MD_Metadata
-from owslib.iso_3 import MD_Metadata as MD_Metadata_3  # ISO 19115 Part 3 XML
+from owslib.iso3 import MD_Metadata as MD_Metadata3  # ISO 19115 Part 3 XML
 from owslib.map.common import WMSCapabilitiesReader, AbstractContentMetadata
 from owslib.namespaces import Namespaces
 
@@ -619,9 +619,9 @@ def parse_remote_metadata(self, timeout=30):
                             metadataUrl['metadata'] = MD_Metadata(mdelem)
                             continue
                         else:  # ISO 19115 Part 3 XML
-                            mdelem = MD_Metadata_3.find_start(doc)
+                            mdelem = MD_Metadata3.find_start(doc)
                             if mdelem is not None:
-                                metadataUrl["metadata"] = MD_Metadata_3(mdelem)
+                                metadataUrl["metadata"] = MD_Metadata3(mdelem)
                             else:
                                 metadataUrl["metadata"] = None
                             continue
diff --git a/owslib/map/wms130.py b/owslib/map/wms130.py
index d2faaf43..ba811366 100644
--- a/owslib/map/wms130.py
+++ b/owslib/map/wms130.py
@@ -23,7 +23,7 @@
                          nspath_eval, bind_url, Authentication)
 from owslib.fgdc import Metadata
 from owslib.iso import MD_Metadata
-from owslib.iso_3 import MD_Metadata as MD_Metadata_3  # ISO 19115 Part 3 XML
+from owslib.iso3 import MD_Metadata as MD_Metadata3  # ISO 19115 Part 3 XML
 from owslib.crs import Crs
 from owslib.namespaces import Namespaces
 from owslib.map.common import WMSCapabilitiesReader, AbstractContentMetadata
@@ -711,9 +711,9 @@ def parse_remote_metadata(self, timeout=30):
                         metadataUrl['metadata'] = MD_Metadata(mdelem)
                         continue
                     else:
-                        mdelem = MD_Metadata_3.find_start(doc)
+                        mdelem = MD_Metadata3.find_start(doc)
                         if mdelem is not None:
-                            metadataUrl["metadata"] = MD_Metadata_3(mdelem)
+                            metadataUrl["metadata"] = MD_Metadata3(mdelem)
                         else:
                             metadataUrl["metadata"] = None
                 except Exception:
diff --git a/tests/test_csw_geonetwork.py b/tests/test_csw_geonetwork.py
index c5f66617..f2e9b464 100644
--- a/tests/test_csw_geonetwork.py
+++ b/tests/test_csw_geonetwork.py
@@ -23,7 +23,7 @@ def test_csw_geonetwork():
 @pytest.mark.skipif(not service_ok(SERVICE_URL3),
                     reason='service is unreachable')
 @pytest.mark.parametrize("esn_in", ['full', 'summary'])
-def test_csw_geonetwork_iso_3(esn_in):
+def test_csw_geonetwork_iso3(esn_in):
     """ Test retrieving records from Belgian geonetwork,
     specifically requesting ISO 19115 Part 3 XML records.
     """
@@ -37,4 +37,4 @@ def test_csw_geonetwork_iso_3(esn_in):
     assert c.results.get('nextrecord') > 0
     assert c.results.get('matches') > 0
     for id in c.records.keys():
-        assert c.records[id].identifier == id
\ No newline at end of file
+        assert c.records[id].identifier == id
diff --git a/tests/test_iso3_parsing.py b/tests/test_iso3_parsing.py
index 9c4a8a21..eba56cdf 100644
--- a/tests/test_iso3_parsing.py
+++ b/tests/test_iso3_parsing.py
@@ -36,7 +36,7 @@
 
 from owslib.etree import etree
 
-from owslib.iso_3 import (MD_Metadata, SV_ServiceIdentification, PT_Locale,
+from owslib.iso3 import (MD_Metadata, SV_ServiceIdentification, PT_Locale,
                           CI_Date, CI_Responsibility, Keyword, MD_Keywords,
                           MD_DataIdentification, MD_Distributor, MD_Distribution,
                           DQ_DataQuality, SV_ServiceIdentification, 
diff --git a/tests/test_remote_metadata.py b/tests/test_remote_metadata.py
index 98099426..85c36b05 100644
--- a/tests/test_remote_metadata.py
+++ b/tests/test_remote_metadata.py
@@ -209,7 +209,7 @@ def openURL(*args, **kwargs):
     return open('tests/resources/csw_dov_getrecordbyid.xml', 'rb')
 
 
-def openURL_3(*args, **kwargs):
+def openURL3(*args, **kwargs):
     """ Used to patch the 'openURL' call, returning ISO 19115 Part 3 XML
     """
     return open('tests/resources/iso3_examples/auscope-3d-model.xml', 'rb')
@@ -314,7 +314,7 @@ def test_wfs_110_noremotemd_parse_all(self, mp_wfs_110_nometadata):
 
     @pytest.mark.parametrize("openURL_in, lib_in", [
         (openURL, owslib.iso.MD_Metadata),
-        (openURL_3, owslib.iso_3.MD_Metadata),
+        (openURL3, owslib.iso3.MD_Metadata),
     ])
     def test_wfs_110_noremotemd_parse_single(self, mp_wfs_110_nometadata, monkeypatch, openURL_in, lib_in):
         """Test the remote metadata parsing for WFS 1.1.0.
@@ -373,7 +373,7 @@ def test_wfs_110_noremotemd_parse_none(self, mp_wfs_110_nometadata):
 
     @pytest.mark.parametrize("openURL_in, lib_in", [
         (openURL, owslib.iso.MD_Metadata),
-        (openURL_3, owslib.iso_3.MD_Metadata),
+        (openURL3, owslib.iso3.MD_Metadata),
     ])
     def test_wfs_110_remotemd_parse_all(self, mp_wfs_110, monkeypatch, openURL_in, lib_in):
         """Test the remote metadata parsing for WFS 1.1.0.
@@ -409,7 +409,7 @@ def test_wfs_110_remotemd_parse_all(self, mp_wfs_110, monkeypatch, openURL_in, l
 
     @pytest.mark.parametrize("openURL_in, lib_in", [
         (openURL, owslib.iso.MD_Metadata),
-        (openURL_3, owslib.iso_3.MD_Metadata),
+        (openURL3, owslib.iso3.MD_Metadata),
     ])
     def test_wfs_110_remotemd_parse_single(self, mp_wfs_110, monkeypatch, openURL_in, lib_in):
         """Test the remote metadata parsing for WFS 1.1.0.
@@ -542,7 +542,7 @@ def test_wfs_200_noremotemd_parse_none(self, mp_wfs_200_nometadata):
 
     @pytest.mark.parametrize("openURL_in, lib_in", [
         (openURL, owslib.iso.MD_Metadata),
-        (openURL_3, owslib.iso_3.MD_Metadata),
+        (openURL3, owslib.iso3.MD_Metadata),
     ])
     def test_wfs_200_remotemd_parse_all(self, mp_wfs_200, monkeypatch, openURL_in, lib_in):
         """Test the remote metadata parsing for WFS 2.0.0.
@@ -579,7 +579,7 @@ def test_wfs_200_remotemd_parse_all(self, mp_wfs_200, monkeypatch, openURL_in, l
 
     @pytest.mark.parametrize("openURL_in, lib_in", [
         (openURL, owslib.iso.MD_Metadata),
-        (openURL_3, owslib.iso_3.MD_Metadata),
+        (openURL3, owslib.iso3.MD_Metadata),
     ])
     def test_wfs_200_remotemd_parse_single(self, mp_wfs_200, monkeypatch, openURL_in, lib_in):
         """Test the remote metadata parsing for WFS 2.0.0.
@@ -711,7 +711,7 @@ def test_wms_111_noremotemd_parse_none(self, mp_wms_111_nometadata):
 
     @pytest.mark.parametrize("openURL_in, lib_in", [
         (openURL, owslib.iso.MD_Metadata),
-        (openURL_3, owslib.iso_3.MD_Metadata),
+        (openURL3, owslib.iso3.MD_Metadata),
     ])
     def test_wms_130_remotemd_parse_all(self, mp_wms_130, monkeypatch, openURL_in, lib_in):
         """Test the remote metadata parsing for WMS 1.3.0.
@@ -747,7 +747,7 @@ def test_wms_130_remotemd_parse_all(self, mp_wms_130, monkeypatch, openURL_in, l
 
     @pytest.mark.parametrize("openURL_in, lib_in", [
         (openURL, owslib.iso.MD_Metadata),
-        (openURL_3, owslib.iso_3.MD_Metadata),
+        (openURL3, owslib.iso3.MD_Metadata),
     ])
     def test_wms_130_remotemd_parse_single(self, mp_wms_130, monkeypatch, openURL_in, lib_in):
         """Test the remote metadata parsing for WMS 1.3.0.