# The shortcut for Subsuperscript doesn't work?

The document for Subsuperscript says that:

To enter a subsuperscript in a notebook, use either Ctrl+_ to begin a regular subscript or Ctrl+^ to begin a regular superscript. After typing the first script, use Ctrl+% to move to the opposite script position. Ctrl+Space moves out of the subscript or superscript position.

This just create a expresion that looks like a symbol with subsuperscript! Specifically, I typed Ctrl+- / Ctrl+6 and a regular subscript / superscript appeared, Ctrl+5 and the opposite script appeared, and after I moved the cursor out of the symbol by pressing and checked its InputForm, what I saw is not something like

Subsuperscript[a, x, y]


but

Subscript[a, x]^y


Snapshot:

What's wrong with it, I misunderstood the document? I use Mathematica 8.0.4 and Windows Vista Home Basic 32bit.

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works as expected with 8.0.4 on OS X 10.6.8 –  Mike Honeychurch Jan 16 '13 at 8:03
The standard procedure (i.e. Ctrl+^ then Ctrl+%) works for me at Win. XP or Win. 7/Math. 8 or 9. May it be the Vista peculiarity? –  Alexei Boulbitch Jan 16 '13 at 8:09
@Szabolcs My keyboard is the same as yours i.e. I actually type Ctrl+6 and then Ctrl+5. Let me add it to the question. –  xzczd Jan 17 '13 at 5:52
@AlexeiBoulbitch A friend of mine reproduced the error with 8.0.4 on Windows 7 64bit… –  xzczd Jan 17 '13 at 5:53
This error also appears in version 7 on Windows Vista 32bit. The StandardForm for Subscript[a, x]^y looks just like that for Subsuperscript[a, x, y], have you checked its InputForm or tried to Set a value to it? –  xzczd Jan 18 '13 at 8:32

It appears that when you use Control-% to create something that looks like $x_a^b$, the underlying box representation will be a SubsuperscriptBox. However, the interpretation of a SubsuperscriptBox["x", "a", "b"] box is the expression Subscript[x, a]^b. The expression Subsuperscript[x, a, b]is formatted as TemplateBox[{"x","a","b"}, "Subsuperscript"]] in StandardForm.