Why does ¨ sit beside the letter instead of on top?

Because ¨ (U+00A8) is a spacing character. It takes up its own slot and never attaches to its neighbor, since it exists to show the mark on its own, say when you're naming the accent. For the letter, use the precomposed ü (U+00FC, byte 252 in Windows-1252). If you're building the text in code, the attaching mark is the combining diaeresis `\u0308` after the u, and NFC normalization turns that pair into ü.

Can I use ¨ as quotation marks in Spanish?

No. ¨ is the diaeresis (diéresis in Spanish), the mark on the u in güe and güi, as in pingüino. For quotes the RAE puts the angular pair « » first, with “ ” for a quote inside a quote. In Windows-1252 « and » are bytes 171 and 187, and in the DOS set they sit at 174 and 175.

Why does Alt+0168 give ¨ and not ¿?

Because the leading zero switches Alt codes from the DOS table to the Windows one. Alt+168 goes through your system's DOS code page, and on US and Western European setups (437 or 850) that slot holds ¿. Alt+0168 uses Windows-1252, where 168 is the diaeresis ¨. If you want a zero-style code for ¿, it's Alt+0191, and both routes insert the same character.

Why is every ¿ an ¨ in my old DOS files?

The file was saved in a DOS code page and is being read as Windows-1252, which puts ¨ at byte 168 where DOS had ¿. The é breaks as well, so ¿Qué? shows up as ¨Qu‚? on screen. Convert the file once: `iconv -f CP850 -t UTF-8 old.txt > new.txt`. Code page 437 also has ¿ at 168, but it lacks Á, Í, Ó and Ú, so 850 is the safer pick for Spanish.

ASCII 168

Diaeresis (umlaut)Inverted question mark

ASCII 168 is ¨ on Windows and ¿ in old DOS.

¨ (Diaeresis) is byte 168 in Windows-1252, Unicode U+00A8. It's the two dots of an umlaut or trema on their own, as a spacing character that doesn't attach to any letter. One place it turns up uninvited: text copied out of a PDF made with LaTeX can read M¨uller instead of Müller, because the old default font encoding (OT1) draws the dots as a separate glyph placed over the u. On the LaTeX side, \usepackage[T1]{fontenc} fixes it at the source. In text you've already extracted, replace ¨ plus vowel with the precomposed letter. In UTF-8 it's C2 A8, and the HTML entity is ¨.

¿ (Inverted Question Mark) is byte 168 in code page 437, the original IBM PC character set, and maps to Unicode U+00BF. Windows-1252 has the diaeresis ¨ at 168, so Spanish DOS text read as Windows-1252 turns ¿Qué? into ¨Qu‚?, since the é breaks too. Code page 850 kept ¿ at 168 too.

SymbolPunctuation

Technical Details

Code Example

</>

#include <stdio.h>

int main(void) {
    /* On Windows (code page 1252) byte 168 is ¨.
       Modern terminals expect UTF-8, so print the code point, not the byte. */
    printf("\u00A8\n");   /* UTF-8: C2 A8 */

    unsigned char b = 168;         /* the raw Windows-1252 byte */
    printf("%d 0x%02X\n", b, b);    /* 168 0xA8 */
    return 0;
}

Code Example

</>

#include <stdio.h>

int main(void) {
    /* Byte 168 is ¿ only on a console using code page 437
       (chcp 437 on Windows, or DOSBox). On a UTF-8 terminal the
       lone byte 0xA8 is invalid and prints as garbage, often �. */
    putchar(168);

    /* char is signed on x86, so a plain char holding 0xA8 is -88.
       Use unsigned char when you compare or index by byte value. */
    char c = (char)168;
    unsigned char u = 168;
    printf("\n%d %d\n", c, u);   /* -88 168 */

    /* Portable: print the Unicode character as UTF-8 instead. */
    printf("\u00BF\n");          /* C2 BF */
    return 0;
}

How to Type It

Windows: Hold Alt and type 0168 on the numeric keypad, with Num Lock on. The leading zero picks the Windows code page. No numeric keypad? In Word, type 00A8 and press Alt+X.
Mac: Press Option+Shift+U.
Linux: In GNOME, or any desktop running IBus, press Ctrl+Shift+U, type a8, then Space. With a Compose key set up, press Compose, quote, space.
Phone: Tap the character at the top of this page to copy it.

How to Type It

Windows: Hold Alt and type 168 on the numeric keypad, with no leading zero. Windows reads it as a DOS code and inserts ¿.

¿ is also ASCII 191 on Windows, which has the full guide.

Frequently Asked Questions

Because ¨ (U+00A8) is a spacing character. It takes up its own slot and never attaches to its neighbor, since it exists to show the mark on its own, say when you're naming the accent. For the letter, use the precomposed ü (U+00FC, byte 252 in Windows-1252). If you're building the text in code, the attaching mark is the combining diaeresis `\u0308` after the u, and NFC normalization turns that pair into ü.
No. ¨ is the diaeresis (diéresis in Spanish), the mark on the u in güe and güi, as in pingüino. For quotes the RAE puts the angular pair « » first, with “ ” for a quote inside a quote. In Windows-1252 « and » are bytes 171 and 187, and in the DOS set they sit at 174 and 175.
Because the leading zero switches Alt codes from the DOS table to the Windows one. Alt+168 goes through your system's DOS code page, and on US and Western European setups (437 or 850) that slot holds ¿. Alt+0168 uses Windows-1252, where 168 is the diaeresis ¨. If you want a zero-style code for ¿, it's Alt+0191, and both routes insert the same character.
The file was saved in a DOS code page and is being read as Windows-1252, which puts ¨ at byte 168 where DOS had ¿. The é breaks as well, so ¿Qué? shows up as ¨Qu‚? on screen. Convert the file once: `iconv -f CP850 -t UTF-8 old.txt > new.txt`. Code page 437 also has ¿ at 168, but it lacks Á, Í, Ó and Ú, so 850 is the safer pick for Spanish.

Frequently Asked Questions

Because the leading zero switches Alt codes from the DOS table to the Windows one. Alt+168 goes through your system's DOS code page, and on US and Western European setups (437 or 850) that slot holds ¿. Alt+0168 uses Windows-1252, where 168 is the diaeresis ¨. If you want a zero-style code for ¿, it's Alt+0191, and both routes insert the same character.
The file was saved in a DOS code page and is being read as Windows-1252, which puts ¨ at byte 168 where DOS had ¿. The é breaks as well, so ¿Qué? shows up as ¨Qu‚? on screen. Convert the file once: `iconv -f CP850 -t UTF-8 old.txt > new.txt`. Code page 437 also has ¿ at 168, but it lacks Á, Í, Ó and Ú, so 850 is the safer pick for Spanish.

ASCII 168

Diaeresis (umlaut)Inverted question mark

ASCII 168 is ¨ on Windows and ¿ in old DOS.

Symbol

Punctuation

#include <stdio.h>

int main(void) {

/* On Windows (code page 1252) byte 168 is ¨.

Modern terminals expect UTF-8, so print the code point, not the byte. */

printf("\u00A8\n"); /* UTF-8: C2 A8 */

unsigned char b = 168; /* the raw Windows-1252 byte */

printf("%d 0x%02X\n", b, b); /* 168 0xA8 */

return 0;

}

#include <stdio.h>

int main(void) {

/* Byte 168 is ¿ only on a console using code page 437

(chcp 437 on Windows, or DOSBox). On a UTF-8 terminal the

lone byte 0xA8 is invalid and prints as garbage, often �. */

putchar(168);

/* char is signed on x86, so a plain char holding 0xA8 is -88.

Use unsigned char when you compare or index by byte value. */

char c = (char)168;

unsigned char u = 168;

printf("\n%d %d\n", c, u); /* -88 168 */

/* Portable: print the Unicode character as UTF-8 instead. */

printf("\u00BF\n"); /* C2 BF */

return 0;

}