diff --git a/ChangeLog b/ChangeLog
index 648c8781..58c176b1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -26,6 +26,7 @@
   im_fastlineuser() is terrible
 - instead, users of the inplace operations need to call im_invalidate() at the
   end of a set of paint actions to trigger an update
+- parent/child -> upstream/downstream in DAG
 
 15/1/10 started 7.21.1
 - added "written" callbacks, used to implement write to non-vips formats
diff --git a/TODO b/TODO
index f97f2b64..a9e009bd 100644
--- a/TODO
+++ b/TODO
@@ -1,21 +1,3 @@
-- we use parent/child a lot, but it's confusing
-
-  imagine building the pipeline 
-  
-  	A + B -> C
-
-  we create A, we create B, we create C, we call im_add ... C is the parent
-  of A and B, since parents have many children (see comment in image.h for
-  GSList *parents)
-
-  however, we make A and B before C, and pixels flow from them to C, so they
-  seem older, argh
-
-  change name scheme from parent/child to upstream/downstream, so A and B are
-  upstream of C, C is downstream of A and B
-
-  clearer expression of arrow direction in DAG
-
 - add a dependency on the icc-profiles package
  
   the vips load/save ops need to search the icc-profile dir 
diff --git a/libvips/include/vips/image.h b/libvips/include/vips/image.h
index 2c6cf10a..d5a3399b 100644
--- a/libvips/include/vips/image.h
+++ b/libvips/include/vips/image.h
@@ -195,18 +195,16 @@ typedef struct _VipsImage {
 	 */
 	GSList *windows;
 
-	/* Parent/child relationships, built from args to im_demand_hint().
-	 * We use these to invalidate pixel buffers on im_invalidate(). Use
-	 * 'serial' to spot circular dependencies.
+	/* Upstream/downstream relationships, built from args to 
+	 * im_demand_hint().
 	 *
-	 * Parents are later in the tree, so it's child1 + child2 -> parent,
-	 * for example. On im_invalidate(), we dispose the caches on all
-	 * parents of an image.
+	 * We use these to invalidate downstream pixel buffers on 
+	 * im_invalidate(). Use 'serial' to spot circular dependencies.
 	 *
 	 * See also hint_set below.
 	 */
-	GSList *parents;
-	GSList *children;
+	GSList *upstream;
+	GSList *downstream;
 	int serial;
 
 	/* Keep a list of recounted GValue strings so we can share hist
@@ -236,8 +234,8 @@ typedef struct _VipsImage {
 	/* Set this when im_demand_hint_array() is called, and check in any
 	 * operation that will demand pixels from the image.
 	 *
-	 * We use im_demand_hint_array() to build the tree of parent/child
-	 * relationships, so it's a mandatory thing.
+	 * We use im_demand_hint_array() to build the tree of
+	 * upstream/downstream relationships, so it's a mandatory thing.
 	 */
 	gboolean hint_set;
 
diff --git a/libvips/include/vips/internal.h b/libvips/include/vips/internal.h
index c2394250..345579c1 100644
--- a/libvips/include/vips/internal.h
+++ b/libvips/include/vips/internal.h
@@ -134,7 +134,6 @@ typedef enum {
 IMAGE *im__convert_saveable( IMAGE *in, 
 	im__saveable_t saveable, gboolean sixteen );
 
-void im__link_make( IMAGE *parent, IMAGE *child );
 void im__link_break_all( IMAGE *im );
 void *im__link_map( IMAGE *im, VSListMap2Fn fn, void *a, void *b );
 
diff --git a/libvips/iofuncs/im_close.c b/libvips/iofuncs/im_close.c
index 19409ef6..ab6b5269 100644
--- a/libvips/iofuncs/im_close.c
+++ b/libvips/iofuncs/im_close.c
@@ -171,7 +171,7 @@ im__close( IMAGE *im )
 	im->generate = NULL;
 	im->stop = NULL;
 
-	/* No more parent/child links.
+	/* No more upstream/downstream links.
 	 */
 	im__link_break_all( im );
 
diff --git a/libvips/iofuncs/im_demand_hint.c b/libvips/iofuncs/im_demand_hint.c
index 6cab0489..25173d86 100644
--- a/libvips/iofuncs/im_demand_hint.c
+++ b/libvips/iofuncs/im_demand_hint.c
@@ -14,6 +14,8 @@
  * 	- gtkdoc comments
  * 5/3/10
  * 	- move link maintenance to im_demand_hint
+ * 8/3/10
+ * 	- rename parent/child as downstream/upstream, much clearer!
  */
 
 /*
@@ -66,48 +68,46 @@
  */
 #define MAX_IMAGES (1000)
 
-/* Make a parent/child link. child is one of parent's inputs.
+/* Make a upstream/downstream link. upstream is one of downstream's inputs.
  */
-void 
-im__link_make( IMAGE *parent, IMAGE *child )
+static void 
+im__link_make( IMAGE *im_up, IMAGE *im_down )
 {
-	g_assert( parent );
-	g_assert( child );
+	g_assert( im_up );
+	g_assert( im_down );
 
-	parent->children = g_slist_prepend( parent->children, child );
-	child->parents = g_slist_prepend( child->parents, parent );
+	im_up->downstream = g_slist_prepend( im_up->downstream, im_down );
+	im_down->upstream = g_slist_prepend( im_down->downstream, im_up );
 
 	/* Propogate the progress indicator.
 	 */
-	if( child->progress && !parent->progress ) 
-		parent->progress = child->progress;
+	if( im_up->progress && !im_down->progress ) 
+		im_down->progress = im_up->progress;
 }
 
-/* Break link. child is one of parent's inputs.
- */
 static void *
-im__link_break( IMAGE *parent, IMAGE *child )
+im__link_break( IMAGE *im_up, IMAGE *im_down )
 {
-	g_assert( parent );
-	g_assert( child );
-	g_assert( g_slist_find( parent->children, child ) );
-	g_assert( g_slist_find( child->parents, parent ) );
+	g_assert( im_up );
+	g_assert( im_down );
+	g_assert( g_slist_find( im_up->downstream, im_down ) );
+	g_assert( g_slist_find( im_down->upstream, im_up ) );
 
-	parent->children = g_slist_remove( parent->children, child );
-	child->parents = g_slist_remove( child->parents, parent );
+	im_up->downstream = g_slist_remove( im_up->downstream, im_down );
+	im_down->upstream = g_slist_remove( im_down->upstream, im_up );
 
 	/* Unlink the progress chain.
 	 */
-	if( parent->progress && parent->progress == child->progress ) 
-		parent->progress = NULL;
+	if( im_down->progress && im_down->progress == im_up->progress ) 
+		im_down->progress = NULL;
 
 	return( NULL );
 }
 
 static void *
-im__link_break_rev( IMAGE *child, IMAGE *parent )
+im__link_break_rev( IMAGE *im_down, IMAGE *im_up )
 {
-	return( im__link_break( parent, child ) );
+	return( im__link_break( im_up, im_down ) );
 }
 
 /* An IMAGE is going ... break all links.
@@ -115,9 +115,9 @@ im__link_break_rev( IMAGE *child, IMAGE *parent )
 void
 im__link_break_all( IMAGE *im )
 {
-	im_slist_map2( im->parents, 
+	im_slist_map2( im->upstream, 
 		(VSListMap2Fn) im__link_break, im, NULL );
-	im_slist_map2( im->children, 
+	im_slist_map2( im->downstream, 
 		(VSListMap2Fn) im__link_break_rev, im, NULL );
 }
 
@@ -135,11 +135,11 @@ im__link_mapp( IMAGE *im, VSListMap2Fn fn, int *serial, void *a, void *b )
 	if( (res = fn( im, a, b )) )
 		return( res );
 
-	return( im_slist_map4( im->parents, 
+	return( im_slist_map4( im->downstream,
 		(VSListMap4Fn) im__link_mapp, fn, serial, a, b ) );
 }
 
-/* Apply a function to an image and all it's parents, direct and indirect. 
+/* Apply a function to an image and all downstream images, direct and indirect. 
  */
 void *
 im__link_map( IMAGE *im, VSListMap2Fn fn, void *a, void *b )
@@ -217,7 +217,7 @@ im_demand_hint_array( IMAGE *im, VipsDemandStyle hint, IMAGE **in )
 	/* im depends on all these ims.
 	 */
 	for( i = 0; i < len; i++ )
-		im__link_make( im, in[i] );
+		im__link_make( in[i], im );
 
 	/* Set a flag on the image to say we remember to call this thing.
 	 * im_generate() and friends check this.
diff --git a/libvips/iofuncs/init.c b/libvips/iofuncs/init.c
index 5fe49ead..ad5e5ef6 100644
--- a/libvips/iofuncs/init.c
+++ b/libvips/iofuncs/init.c
@@ -161,8 +161,8 @@ im_init( const char *filename )
 
 	im->windows = NULL;
 
-	im->parents = NULL;
-	im->children = NULL;
+	im->upstream = NULL;
+	im->downstream = NULL;
 	im->serial = 0;
 
 	im->history_list = NULL;