diff --git a/headers/private/graphics/radeon/accelerant_ext.h b/headers/private/graphics/radeon/accelerant_ext.h
new file mode 100644
index 0000000000..ed6b1aba1a
--- /dev/null
+++ b/headers/private/graphics/radeon/accelerant_ext.h
@@ -0,0 +1,40 @@
+/*
+	Copyright (c) 2002, Thomas Kurschel
+
+
+	Part of Radeon accelerant
+		
+	additional accelerant interface definitions
+*/
+
+
+#ifndef _ACCELERANT_EXT_H
+#define _ACCELERANT_EXT_H
+
+
+// additional timing flags for GetMode/SetMode
+enum {
+	RADEON_MODE_STANDARD = 0 << 16,
+	RADEON_MODE_MIRROR = 1 << 16,
+	RADEON_MODE_CLONE = 2 << 16,
+	RADEON_MODE_COMBINE = 3 << 16,
+	
+	RADEON_MODE_MASK = 7 << 16,
+	
+	// used internally
+	RADEON_MODE_POSITION_HORIZONTAL = 0 << 21,
+	RADEON_MODE_POSITION_VERTICAL = 1 << 21,
+	RADEON_MODE_POSITION_MASK = 1 << 21,
+	
+	RADEON_MODE_MULTIMON_REQUEST = 1 << 25,
+	RADEON_MODE_MULTIMON_REPLY = 1 << 26
+};
+
+// operation codes tunneled via ProposeDisplayMode
+typedef enum {
+	ms_swap,
+	ms_overlay_port
+} multi_mon_settings;
+
+
+#endif
diff --git a/headers/private/graphics/radeon/multimon.h b/headers/private/graphics/radeon/multimon.h
new file mode 100644
index 0000000000..b9d043ef64
--- /dev/null
+++ b/headers/private/graphics/radeon/multimon.h
@@ -0,0 +1,19 @@
+/*
+	Copyright (c) 2002, Thomas Kurschel
+	
+
+	Part of Radeon driver
+		
+	Multi-Monitor Settings interface
+*/
+
+#ifndef _MULTIMON_H
+#define _MULTIMON_H
+
+class BScreen;
+
+status_t GetSwapDisplays( BScreen *screen, bool *swap );
+status_t SetSwapDisplays( BScreen *screen, bool swap );
+status_t TestMultiMonSupport( BScreen *screen );
+
+#endif