More doc strings

git-svn-id: https://svn.erp5.org/repos/public/erp5/sandbox/amount_generator@34928 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/interfaces/expandable.py

@@ -35,11 +35,27 @@ from zope.interface import Interface
 class IExpandable(Interface):
   """
     An Expandable class provides methods which trigger
-    the generation of a root applied rule in the simulation
-    and its expansion.
+    the generation of the root applied rule of a simulation tree
+    and its expansion. Classes which implement IExpand include
+    Deliveries (whenever can be the cause of an Applied Rule),
+    Items (whenever they  are the cause of a movement sequence)
+    such as Subscription Items or Immobilisation Items, Movements
+    (which have been previously built).
   """
 
-  def expand(applied_rule_id=None, force=0, activate_kw=None, **kw):
+  def expand(applied_rule_id=None, force=False, activate_kw=None, **kw):
     """
-      Expand the current Expandable class into the simulation
+      Expand the current Expandable class into the simulation.
+      If no applied_rule_id is provided, try first to find 
+      appropriate applied rule if any to start expansion process.
+
+      applied_rule_id -- a hint parameter (optional), which can
+                         be provided to reindex the whole 
+                         simulation tree from the root applied rule
+
+      force -- (LEGACY) this named parameter is no longer used. It
+               used to be required because of unclear specification
+               of expand stability
+
+      activate_kw -- (TO BE EXPLAINED BY KAZ)
     """