+ * There are several sets of changes which could be considered incompatible
+ * between two transactions which are derived from same initial state.
+ * Rules for conflict detection applies recursively for each subtree
+ * level.
+ *
+ * <h4>Change compatibility of leafs, leaf-list items</h4>
+ *
+ * Following table shows state changes and failures between two concurrent transactions,
+ * which are based on same initial state, Tx 1 completes successfully
+ * before Tx 2 is submitted.
+ *
+ * <table>
+ * <tr><th>Initial state</th><th>Tx 1</th><th>Tx 2</th><th>Result</th></tr>
+ * <tr><td>Empty</td><td>put(A,1)</td><td>put(A,2)</td><td>Tx 2 will fail, state is A=1</td></tr>
+ * <tr><td>Empty</td><td>put(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
+ *
+ * <tr><td>Empty</td><td>merge(A,1)</td><td>put(A,2)</td><td>Tx 2 will fail, state is A=1</td></tr>
+ * <tr><td>Empty</td><td>merge(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
+ *
+ *
+ * <tr><td>A=0</td><td>put(A,1)</td><td>put(A,2)</td><td>Tx 2 will fail, A=1</td></tr>
+ * <tr><td>A=0</td><td>put(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
+ * <tr><td>A=0</td><td>merge(A,1)</td><td>put(A,2)</td><td>Tx 2 will fail, A=1</td></tr>
+ * <tr><td>A=0</td><td>merge(A,1)</td><td>merge(A,2)</td><td>A=2</td></tr>
+ *
+ * <tr><td>A=0</td><td>delete(A)</td><td>put(A,2)</td><td>Tx 2 will fail, A does not exists</td></tr>
+ * <tr><td>A=0</td><td>delete(A)</td><td>merge(A,2)</td><td>A=2</td></tr>
+ * </table>
+ *
+ * <h4>Change compatibility of subtrees</h4>
+ *
+ * Following table shows state changes and failures between two concurrent transactions,
+ * which are based on same initial state, Tx 1 completes successfully
+ * before Tx 2 is submitted.
+ *
+ * <table>
+ * <tr><th>Initial state</th><th>Tx 1</th><th>Tx 2</th><th>Result</th></tr>
+ *
+ * <tr><td>Empty</td><td>put(TOP,[])</td><td>put(TOP,[])</td><td>Tx 2 will fail, state is TOP=[]</td></tr>
+ * <tr><td>Empty</td><td>put(TOP,[])</td><td>merge(TOP,[])</td><td>TOP=[]</td></tr>
+ *
+ * <tr><td>Empty</td><td>put(TOP,[FOO=1])</td><td>put(TOP,[BAR=1])</td><td>Tx 2 will fail, state is TOP=[FOO=1]</td></tr>
+ * <tr><td>Empty</td><td>put(TOP,[FOO=1])</td><td>merge(TOP,[BAR=1])</td><td>TOP=[FOO=1,BAR=1]</td></tr>
+ *
+ * <tr><td>Empty</td><td>merge(TOP,[FOO=1])</td><td>put(TOP,[BAR=1])</td><td>Tx 2 will fail, state is TOP=[FOO=1]</td></tr>
+ * <tr><td>Empty</td><td>merge(TOP,[FOO=1])</td><td>merge(TOP,[BAR=1])</td><td>TOP=[FOO=1,BAR=1]</td></tr>