diff --git a/docs/index.html b/docs/index.html
index 837b7e1..1e13cf8 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -9,7 +9,7 @@
 
 <div align=right class=lastmod>
 <!-- hhmts start -->
-Last Modified: Wed Jun 25 10:27:52 UTC 2014
+Last Modified: Mon Sep 26 09:04:15 UTC 2016
 <!-- hhmts end -->
 </div>
 
@@ -268,6 +268,7 @@ are M = 2.0, L = 0.5, and W = 0.1, respectively.
 <dd> Specifies how much a horizontal and vertical position of a text matters
 when determining a text order. The value should be within the range of 
 -1.0 (only horizontal position matters) to +1.0 (only vertical position matters).
+When this value is out of the range (e.g. +2), a simpler ordering rule is used.
 The default value is 0.5.
 <p>
 <dt> <code>-C</code> 
diff --git a/pdfminer/layout.py b/pdfminer/layout.py
index 9426ad3..6477eff 100644
--- a/pdfminer/layout.py
+++ b/pdfminer/layout.py
@@ -676,13 +676,20 @@ class LTLayoutContainer(LTContainer):
         for obj in empties:
             obj.analyze(laparams)
         textboxes = list(self.group_textlines(laparams, textlines))
-        if textboxes:
+        if -1 <= laparams.boxes_flow and laparams.boxes_flow <= +1 and textboxes:
             self.groups = self.group_textboxes(laparams, textboxes)
             assigner = IndexAssigner()
             for group in self.groups:
                 group.analyze(laparams)
                 assigner.run(group)
             textboxes.sort(key=lambda box: box.index)
+        else:
+            def getkey(box):
+                if isinstance(box, LTTextBoxVertical):
+                    return (0, -box.x1, box.y0)
+                else:
+                    return (1, box.y0, box.x0)
+            textboxes.sort(key=getkey)
         self._objs = textboxes + otherobjs + empties
         return
 
@@ -725,4 +732,4 @@ class LTPage(LTLayoutContainer):
     def __repr__(self):
         return ('<%s(%r) %s rotate=%r>' %
                 (self.__class__.__name__, self.pageid,
-                 bbox2str(self.bbox), self.rotate))
\ No newline at end of file
+                 bbox2str(self.bbox), self.rotate))