diff --git a/Apple-GCR-disk-encoding.md b/Apple-GCR-disk-encoding.md
index 33f3274..289de25 100644
--- a/Apple-GCR-disk-encoding.md
+++ b/Apple-GCR-disk-encoding.md
@@ -131,4 +131,4 @@ The most common type of Apple disk image — variously DSK, DO, PO and other ext
 
 Therefore the proper physical interpretation of that sort of disk image is tightly coupled to the internals of the specific software that created it.
 
-Specifically, on-disk sectors 0 to 15 of a DOS 3.3 image (ordinarily having the extension DSK or DO) should contain the contents of the image sectors at offsets: `0, 7, 14, 6, 13, 5, 12, 4, 11, 3, 10, 2, 9, 1, 8, 15` — i.e. increase by 7 at each step, and take the modulo by 15 if out of bounds. The on-disk sectors 0 to 15 of a Pro-DOS image (ordinarily PO) should contain the sectors at offsets `0, 8, 1, 9, 2, 10, 3, 11, 4, 12, 5, 13, 6, 14, 7, 15` — i.e. increase by 8 each step, and take the module by 15 if out of bounds.
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+Specifically, on-disk sectors 0 to 15 of a DOS 3.3 image (ordinarily having the extension DSK or DO) should contain the contents of the image sectors at offsets: `0, 7, 14, 6, 13, 5, 12, 4, 11, 3, 10, 2, 9, 1, 8, 15` — i.e. increase by 7 at each step, and take the modulo by 15 if out of bounds. The on-disk sectors 0 to 15 of a Pro-DOS image (ordinarily PO) should contain the sectors at offsets `0, 8, 1, 9, 2, 10, 3, 11, 4, 12, 5, 13, 6, 14, 7, 15` — i.e. increase by 8 each step, and take the modulo by 15 if out of bounds.
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