2 files changed, 31 insertions, 4 deletions
diff --git a/system/doc/design_principles/spec_proc.xml b/system/doc/design_principles/spec_proc.xml
index 3d7a88da3f..5b156ac263 100644
--- a/system/doc/design_principles/spec_proc.xml
+++ b/system/doc/design_principles/spec_proc.xml
@@ -4,7 +4,7 @@
 <chapter>
   <header>
     <copyright>
-      <year>1997</year><year>2014</year>
+      <year>1997</year><year>2016</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -522,9 +522,36 @@ init(Parent, Name, Module) ->
 -module(db).
 -behaviour(simple_server).
 
--export([init/0, handle_req/2, terminate/0]).
+-export([init/1, handle_req/2, terminate/0]).
 
 ...</code>
+
+    <p>The contracts specified with <c>-callback</c> attributes in
+    behaviour modules can be further refined by adding <c>-spec</c>
+    attributes in callback modules. This can be useful as
+    <c>-callback</c> contracts are usually generic. The same callback
+    module with contracts for the callbacks:</p>
+    
+    <code type="none">
+-module(db).
+-behaviour(simple_server).
+
+-export([init/1, handle_req/2, terminate/0]).
+
+-record(state, {field1 :: [atom()], field2 :: integer()}).
+
+-type state()   :: #state{}.
+-type request() :: {'store', term(), term()};
+                   {'lookup', term()}.
+
+...
+
+-spec handle_req(request(), state()) -> {'ok', term()}.
+
+...</code>
+
+    <p>Each <c>-spec</c> contract is to be a subtype of the respective
+    <c>-callback</c> contract.</p>
+    
   </section>
 </chapter>
-
diff --git a/system/doc/design_principles/sup_princ.xml b/system/doc/design_principles/sup_princ.xml
index 5e2f6ba9cb..08c4b7c59e 100644
--- a/system/doc/design_principles/sup_princ.xml
+++ b/system/doc/design_principles/sup_princ.xml
@@ -229,7 +229,7 @@ child_spec() = #{id => child_id(),       % mandatory
           is <c>rest_for_one</c> or <c>one_for_all</c> and a sibling
           death causes the temporary process to be terminated).</item>
           <item>A <c>transient</c> child process is restarted only if it
-	  terminates abnormally, that is, with another exit reason than
+	  terminates abnormally, that is, with an exit reason other than
           <c>normal</c>, <c>shutdown</c>, or <c>{shutdown,Term}</c>.</item>
         </list>
 	<p>The <c>restart</c> key is optional. If it is not given, the