--- a/README	Fri May 26 18:27:59 2017 +0200
+++ b/README	Mon May 29 16:39:32 2017 +0200
@@ -117,6 +117,8 @@
 
  - olog: add an 'obslog' alias
  - olog: add an '--all' option to show the whole obsolescence history tree.
+ - evolution: add an experiment to track the effect of rewrites.
+   (See hg help - evolve for details)
  - template: add a 'precursors' template that display the closests precursors of changesets
  - template: add a 'successors' template that display the closests successors of changesets
  - template: add a 'obsfate' template that display how a changeset has evolved

--- a/hgext3rd/evolve/__init__.py	Fri May 26 18:27:59 2017 +0200
+++ b/hgext3rd/evolve/__init__.py	Mon May 29 16:39:32 2017 +0200
@@ -77,6 +77,23 @@
 
     [extensions]
     blackbox =
+
+Effect Flag Experiment
+======================
+
+We are experimenting with a way to register what changed between a precursor
+and its successors (content, description, parent, etc...). For example, having
+this information is helpful to show what changed between an obsolete changeset
+and its tipmost successors.
+
+The following config control the experiment::
+
+  [experimental]
+  # activate the registration of effect flags in obs markers
+  evolution.effect-flags = yes
+
+The effect flags are shown in the obglog command output without particular
+configuration of you want to inspect them.
 """
 
 evolutionhelptext = """