Differences

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+====== IOP.SPTR ======
+This trap sets the pointer position.
+^Call Parameters^^Return Parameters^^
+| D0.B | $7B | D0.L | Error return |
+| D1.L | x,y coordinates | D1.L | x,y coordinates|
+| D2.W | Origin key | D2.L | Preserved |
+| D3.W | Timeout | D3.L | Preserved |
+| A0.L | Channel ID | A0.L | Preserved |
+==== Errors ====
+|ERR_NO|Channel not open|
+|ER_OR| Out of range|
+==== Notes ====
+  * All registers not mentioned above are preserved.
+  * The origin key in D2.W has the following effect:
+    * -1 sets the pointer relative to the current window definition.
+    *  0 sets the pointer to the absolute position in D1.
+    *  1 sets the pointer relative to the hit area.
+  * The position returned in D1 is in absolute coordinates.
+==== Example ====
+The example here shows the pointer set to the top left of the screen. It is assumed that on entry A4 points to the working definition.
+<code>
+        movea.l    ww_chid(a4),a0   ; Set the channel ID (ww_chid = 8)
+        moveq      #0,d1            ; Position 0,0 . .
+        moveq      #9,d2            ; . . absolute
+        moveq      #IOP_SPTR,d0
+        trap       #3
+        tst.l      d0               ; Errors? . .
+        bne        err ---->        ; . . yes!
+</code>