Removed a "self" argument. self is normally not shown in interfaces.

Removed the freeme argument.  This argument is part of the
implementation, not the public interface.

Removed the subtransaction argument.  Although it is still supported,
it isn't part of the pblic interface.

Added missing documentation of the savepoint method.

src/transaction/interfaces.py

@@ -39,10 +39,21 @@ class ITransactionManager(zope.interface.Interface):
         """Commit the current transaction
         """
 
-    def abort(self):
+    def abort():
         """Abort the current transaction
         """
 
+    def savepoint(optimistic=False):
+        """Create a savepoint from the current transaction.
+
+        If the optimistic argument is true, then data managers that
+        don't support savepoints can be used, but an error will be
+        raised if the savepoint is rolled back.
+
+        An ISavepoint object is returned.
+        """
+        
+
     def registerSynch(synch):
         """Register an ISynchronizer.
 
@@ -91,20 +102,30 @@ class ITransaction(zope.interface.Interface):
         raise an exception, or truncate the value).
         """)
 
-    def commit(subtransaction=None):
+    def commit():
         """Finalize the transaction.
 
         This executes the two-phase commit algorithm for all
         IDataManager objects associated with the transaction.
         """
 
-    def abort(subtransaction=0, freeme=1):
+    def abort():
         """Abort the transaction.
 
         This is called from the application.  This can only be called
         before the two-phase commit protocol has been started.
         """
 
+    def savepoint(optimistic=False):
+        """Create a savepoint.
+
+        If the optimistic argument is true, then data managers that
+        don't support savepoints can be used, but an error will be
+        raised if the savepoint is rolled back.
+
+        An ISavepoint object is returned.
+        """
+
     def join(datamanager):
         """Add a datamanager to the transaction.