diff --git a/ChangeLog b/ChangeLog
index c040394bd..dda891bf4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2000-10-27  Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Source/NSURLHandle.m: Make class registration thread safe.
+	Tidy initialisation to use designated initialiser.
+
 2000-10-27  Adam Fedor  <fedor@gnu.org>
 
 	* Added localization support
diff --git a/Documentation/gsdoc/NSURL.gsdoc b/Documentation/gsdoc/NSURL.gsdoc
index 2c23f2e32..66c0c47ca 100644
--- a/Documentation/gsdoc/NSURL.gsdoc
+++ b/Documentation/gsdoc/NSURL.gsdoc
@@ -51,6 +51,22 @@
           <sel>usingCache:</sel>
           <arg type="BOOL">shouldUseCache</arg>
           <desc>
+	    Loads the resource data for the specified URL.
+	    <p>
+	      If <em>shouldUseCache</em> is <code>YES</code> then an attempt
+	      will be made to locate a cached NSURLHandle to provide the
+	      resource data, otherwise a new handle will be created and
+	      cached.
+	    </p>
+	    <p>
+	      If the handle does not have the data available, it will be
+	      asked to load the data in the background by calling its
+	      loadInBackground  method.
+	    </p>
+	    <p>
+	      The specified client (if non-nil) will be set up to recieve
+	      notifications of the progress fo the background load process.
+	    </p>
           </desc>
         </method>
 
diff --git a/Documentation/gsdoc/NSURL.html b/Documentation/gsdoc/NSURL.html
index 59dbd7fd6..7f789fecf 100644
--- a/Documentation/gsdoc/NSURL.html
+++ b/Documentation/gsdoc/NSURL.html
@@ -71,6 +71,28 @@
 <h3><a name ="method-3">loadResourceDataNotifyingClient:usingCache:</a></h3>
 - (void) <b>loadResourceDataNotifyingClient:</b> (id)client <b>usingCache:</b> (BOOL)shouldUseCache;<br>
 
+	    Loads the resource data for the specified URL.
+	    <p>
+
+	      If <em>shouldUseCache</em> is <code>YES</code> then an attempt
+	      will be made to locate a cached NSURLHandle to provide the
+	      resource data, otherwise a new handle will be created and
+	      cached.
+	    </p>
+
+	    <p>
+
+	      If the handle does not have the data available, it will be
+	      asked to load the data in the background by calling its
+	      loadInBackground  method.
+	    </p>
+
+	    <p>
+
+	      The specified client (if non-nil) will be set up to recieve
+	      notifications of the progress fo the background load process.
+	    </p>
+
           
  <hr>
 <h3><a name ="method-4">parameterString</a></h3>
diff --git a/Source/NSURL.m b/Source/NSURL.m
index 62ad5aff3..344c46c02 100644
--- a/Source/NSURL.m
+++ b/Source/NSURL.m
@@ -591,7 +591,6 @@ NSString	*NSURLPartKey_query = @"query";
   NSLog(@"*_baseURL: %@", [[url baseURL] description]);
 }
 
-//-----------------------------------------------------------------------------
 - (void) loadResourceDataNotifyingClient: (id)client
 			      usingCache: (BOOL)shouldUseCache
 {
@@ -635,7 +634,6 @@ NSString	*NSURLPartKey_query = @"query";
   return data;
 }
 
-//-----------------------------------------------------------------------------
 - (NSURLHandle*) URLHandleUsingCache: (BOOL)shouldUseCache
 {
   NSURLHandle	*handle = nil;
@@ -657,15 +655,13 @@ NSString	*NSURLPartKey_query = @"query";
   return handle;
 }
 
-//-----------------------------------------------------------------------------
 - (BOOL) setResourceData: (NSData*)data
 {
   NSURLHandle	*handle = [self URLHandleUsingCache: YES];
 
-  return [handle writeData: data];
+  return (handle == nil) ? NO : [handle writeData: data];
 }
 
-//-----------------------------------------------------------------------------
 - (id) propertyForKey: (NSString*)propertyKey
 {
   NSURLHandle	*handle = [self URLHandleUsingCache: YES];
@@ -673,7 +669,6 @@ NSString	*NSURLPartKey_query = @"query";
   return [handle propertyForKey: propertyKey];
 }
 
-//-----------------------------------------------------------------------------
 - (BOOL) setProperty: (id)property
 	      forKey: (NSString*)propertyKey;
 {
diff --git a/Source/NSURLHandle.m b/Source/NSURLHandle.m
index ee8293e3b..e2ea71aa8 100644
--- a/Source/NSURLHandle.m
+++ b/Source/NSURLHandle.m
@@ -31,6 +31,7 @@
 #include <Foundation/NSString.h>
 #include <Foundation/NSException.h>
 #include <Foundation/NSConcreteNumber.h>
+#include <Foundation/NSLock.h>
 #include <Foundation/NSURLHandle.h>
 #include <Foundation/NSURL.h>
 #include <Foundation/NSMapTable.h>
@@ -39,7 +40,9 @@
 
 @implementation NSURLHandle
 
+static NSLock		*registryLock = nil;
 static NSMutableArray	*registry = nil;
+static Class		NSURLHandleClass = 0;
 
 + (NSURLHandle*) cachedHandleForURL: (NSURL*)url
 {
@@ -47,11 +50,18 @@ static NSMutableArray	*registry = nil;
    * Each subclass is supposed to do its own caching, so we must
    * find the correct subclass and ask it for its cached handle.
    */
-  if (self == [NSURLHandle class])
+  if (self == NSURLHandleClass)
     {
       Class	c = [self URLHandleClassForURL: url];
 
-      return [c cachedHandleForURL: url];
+      if (c == self || c == 0)
+	{
+	  return nil;
+	}
+      else
+	{
+	  return [c cachedHandleForURL: url];
+	}
     }
   else
     {
@@ -72,7 +82,9 @@ static NSMutableArray	*registry = nil;
 {
   if (self == [NSURLHandle class])
     {
+      NSURLHandleClass = self;
       registry = [NSMutableArray new];
+      registryLock = [NSLock new];
       [self registerURLHandleClass: [GSFileURLHandle class]];
     }
 }
@@ -84,13 +96,18 @@ static NSMutableArray	*registry = nil;
    * Re-adding a class moves it to the end of the registry - so it will
    * be used in preference to any class added earlier.
    */
+  [registryLock lock];
   [registry removeObjectIdenticalTo: urlHandleSubclass];
   [registry addObject: urlHandleSubclass];
+  [registryLock unlock];
 }
 
 + (Class) URLHandleClassForURL: (NSURL*)url
 {
-  unsigned	count = [registry count];
+  unsigned	count;
+
+  [registryLock lock];
+  count = [registry count];
 
   /*
    * Find a class to handle the URL, try most recently registered first.
@@ -101,9 +118,11 @@ static NSMutableArray	*registry = nil;
 
       if ([found canInitWithURL: url] == YES)
 	{
+	  [registryLock unlock];
 	  return (Class)found;
 	}
     }
+  [registryLock unlock];
   return 0;
 }
 
@@ -245,17 +264,16 @@ static NSMutableArray	*registry = nil;
 
 - (id) init
 {
-  _status = NSURLHandleNotLoaded;
-  _clients = [NSMutableArray new];
-  _data = [NSMutableData new];
-  return self;
+  return [self initWithURL: nil cached: NO];
 }
 
 - (id) initWithURL: (NSURL*)url
 	    cached: (BOOL)cached
 {
-  [self subclassResponsibility: _cmd];
-  return nil;
+  _status = NSURLHandleNotLoaded;
+  _clients = [NSMutableArray new];
+  _data = [NSMutableData new];
+  return self;
 }
 
 - (void) loadInBackground
@@ -394,14 +412,13 @@ static NSMutableDictionary	*fileCache = nil;
 	  return self;
 	}
     }
-  self = [super init];
-  if (self != nil)
+
+  if ((self = [super initWithURL: url cached: cached]) != nil)
     {
       _path = [path copy];
       if (cached == YES)
 	{
 	  [fileCache setObject: self forKey: _path];
-	  RELEASE(self);
 	}
     }
   return self;