diff --git a/mercurial/obsolete.py b/mercurial/obsolete.py
--- a/mercurial/obsolete.py
+++ b/mercurial/obsolete.py
@@ -1043,6 +1043,11 @@
     if useoperation and operation:
         metadata['operation'] = operation
 
+    # Effect flag metadata handling
+    saveeffectflag = repo.ui.configbool('experimental',
+                                        'effect-flags',
+                                        False)
+
     tr = repo.transaction('add-obsolescence-marker')
     try:
         markerargs = []
@@ -1066,6 +1071,13 @@
                 raise error.Abort(_("changeset %s cannot obsolete itself")
                                   % prec)
 
+            # Effect flag can be different by relation
+            if saveeffectflag:
+                # The effect flag is saved in a versioned field name for future
+                # evolution
+                effectflag = obsutil.geteffectflag(rel)
+                localmetadata[obsutil.EFFECTFLAGFIELD] = "%d" % effectflag
+
             # Creating the marker causes the hidden cache to become invalid,
             # which causes recomputation when we ask for prec.parents() above.
             # Resulting in n^2 behavior.  So let's prepare all of the args
diff --git a/mercurial/obsutil.py b/mercurial/obsutil.py
--- a/mercurial/obsutil.py
+++ b/mercurial/obsutil.py
@@ -305,6 +305,19 @@
             foreground = set(repo.set('%ln::', known))
     return set(c.node() for c in foreground)
 
+# logic around storing and using effect flags
+EFFECTFLAGFIELD = "ef1"
+
+def geteffectflag(relation):
+    """ From an obs-marker relation, compute what changed between the
+    predecessor and the successor.
+    """
+    effects = 0
+
+    source = relation[0]
+
+    return effects
+
 def getobsoleted(repo, tr):
     """return the set of pre-existing revisions obsoleted by a transaction"""
     torev = repo.unfiltered().changelog.nodemap.get