Index: build/property.jam
===================================================================
--- build/property.jam	(revision 48386)
+++ build/property.jam	(working copy)
@@ -609,8 +609,8 @@
         local best = [ sequence.select-highest-ranked $(matches)
             : $(match-ranks) ] ;
         if $(best[2])
-        {
-            errors.error "Ambiguous key" ;
+        {            
+            errors.error "Ambiguous key for" $(properties) ;
         }
         local original = $(self.value.$(best)) ;
         if $(value)
Index: tools/types/obj.jam
===================================================================
--- tools/types/obj.jam	(revision 48386)
+++ tools/types/obj.jam	(working copy)
@@ -1,5 +1,9 @@
 # Copyright David Abrahams 2004. Distributed under the Boost
 # Software License, Version 1.0. (See accompanying
 # file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-type OBJ : obj : : NT CYGWIN ;
-type OBJ : o ;
+
+import type ;
+
+type.register OBJ : o obj ;
+type.set-generated-target-suffix OBJ : <target-os>windows : obj ;
+type.set-generated-target-suffix OBJ : <target-os>cygwin : obj ;
Index: tools/types/exe.jam
===================================================================
--- tools/types/exe.jam	(revision 48386)
+++ tools/types/exe.jam	(working copy)
@@ -1,5 +1,9 @@
 # Copyright David Abrahams 2004. Distributed under the Boost
 # Software License, Version 1.0. (See accompanying
 # file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
-type EXE : exe : : NT CYGWIN ;
-type EXE ;
+
+import type ;
+
+type.register EXE ;
+type.set-generated-target-suffix EXE : <target-os>windows : "exe" ;
+type.set-generated-target-suffix EXE : <target-os>cygiwn : "exe" ;
Index: tools/types/lib.jam
===================================================================
--- tools/types/lib.jam	(revision 48386)
+++ tools/types/lib.jam	(working copy)
@@ -7,23 +7,25 @@
 
 type.register LIB ;
 
-if [ os.on-unix ]
-{
-    type.set-generated-target-prefix LIB : : "lib" ;
-}
+type.set-generated-target-prefix LIB : : "lib" ;
+type.set-generated-target-prefix LIB : <target-os>windows : "" ;
+type.set-generated-target-prefix LIB : <target-os>cygwin : "" ;
 
-type STATIC_LIB : lib a : LIB : NT CYGWIN ;
-type STATIC_LIB : a : LIB : MACOSX ;
-type STATIC_LIB : a : LIB ;
+# FIXME: should not register both extensions on both
+# platforms.
+type.register STATIC_LIB : a lib : LIB ;
+
+type.set-generated-target-suffix STATIC_LIB : <target-os>windows : lib ;
+type.set-generated-target-suffix STATIC_LIB : <target-os>cygwin : lib ;
 type.set-generated-target-prefix STATIC_LIB : : lib ;
 
 type IMPORT_LIB : : STATIC_LIB ;
 type.set-generated-target-suffix IMPORT_LIB : : lib ;
 type.set-generated-target-prefix IMPORT_LIB : : "" ;
 
-type SHARED_LIB : dll : LIB : NT CYGWIN ;
-type SHARED_LIB : dylib : LIB : MACOSX ;
-type SHARED_LIB : so : LIB ;
+type.register SHARED_LIB : so dll dylib : LIB ;
+type.set-generated-target-suffix SHARED_LIB : <target-os>windows : dll ;
+type.set-generated-target-suffix SHARED_LIB : <target-os>darwin : dylib ;
 
 type SEARCHED_LIB : : LIB ;
 # This is needed so that when we create a target of SEARCHED_LIB