Changed some XML tags as per discussions with CCSDS nav team.

src/main/java/org/orekit/files/ccsds/ndm/odm/ocm/CovarianceHistoryWriter.java

@@ -47,7 +47,7 @@ class CovarianceHistoryWriter extends AbstractWriter {
      */
     CovarianceHistoryWriter(final CovarianceHistory covarianceHistory,
                             final TimeConverter timeConverter) {
-        super(OcmDataSubStructureKey.covar.name(), OcmDataSubStructureKey.COV.name());
+        super(OcmDataSubStructureKey.cov.name(), OcmDataSubStructureKey.COV.name());
         this.history       = covarianceHistory;
         this.timeConverter = timeConverter;
     }

src/main/java/org/orekit/files/ccsds/ndm/odm/ocm/OcmDataSubStructureKey.java

@@ -41,7 +41,7 @@ public enum OcmDataSubStructureKey {
     COV((token, parser) -> parser.manageCovarianceHistorySection(token.getType() == TokenType.START)),
 
     /** Covariance time history section. */
-    covar((token, parser) -> parser.manageCovarianceHistorySection(token.getType() == TokenType.START)),
+    cov((token, parser) -> parser.manageCovarianceHistorySection(token.getType() == TokenType.START)),
 
     /** Maneuvers section. */
     MAN((token, parser) -> parser.manageManeuversSection(token.getType() == TokenType.START)),
@@ -65,7 +65,7 @@ public enum OcmDataSubStructureKey {
     USER((token, parser) -> parser.manageUserDefinedParametersSection(token.getType() == TokenType.START)),
 
     /** User-defined parameters section. */
-    userDef((token, parser) -> parser.manageUserDefinedParametersSection(token.getType() == TokenType.START));
+    user((token, parser) -> parser.manageUserDefinedParametersSection(token.getType() == TokenType.START));
 
     /** Processing method. */
     private final TokenProcessor processor;

src/main/java/org/orekit/files/ccsds/ndm/odm/ocm/OcmWriter.java

@@ -134,7 +134,7 @@ public class OcmWriter extends AbstractMessageWriter<Header, Segment<OcmMetadata
 
         if (segment.getData().getUserDefinedBlock() != null) {
             // write optional user defined parameters block
-            new UserDefinedWriter(OcmDataSubStructureKey.userDef.name(),
+            new UserDefinedWriter(OcmDataSubStructureKey.user.name(),
                                   OcmDataSubStructureKey.USER.name(),
                                   segment.getData().getUserDefinedBlock()).
             write(generator);

src/test/resources/ccsds/odm/ocm/OCMExample2.xml

@@ -58,9 +58,9 @@
            <FIXED_F10P7>105.0</FIXED_F10P7>
            <FIXED_F10P7_MEAN>120.0</FIXED_F10P7_MEAN>
         </pert>
-        <userDef>
+        <user>
            <USER_DEFINED parameter="EARTH_MODEL">WGS-84</USER_DEFINED>
-        </userDef>
+        </user>
       </data>
     </segment>
   </body>