I'm assuming you know what you're doing, but
it's perhaps worth
pointing
out that when (per the instructions on
http://www.wikipedia.com/wiki.cgi?Wiki_ASCII_codes_page )
I hold down alt key and then, using the number pad, type the number
of
the character in question, I do indeed get the
character in question.
I'm fairly sure it works the same way for many other people, too.
It gets complicated, because the Alt-Number trick gives different
results whether you use 3 or 4 digits. Before Windows 1.0, MS-DOS
used national code pages, so typing Alt-151, for example, would
produce code 151, which in the standard code page of the time was u-
grave. By the time Windows came around, ISO-8859-1 had become a much
more prominent standard, and it was decided that WIndows fonts would
use that encoding. But since people were used to Alt-XXX doing
certain things, Windows grabs those and translates them into the ISO
equivalent of what used to be at that position, so when you type Alt-
151, you really get character 249, u-grave (the ISO code). This is
what's on the ASCII codes page, and why it works for most Windows/ISO
machines, but it's misleading. Your chart shows "151" next to what
is actually character 249 (look the file in hex if you doubt this).
Now, since ISO-8859 leaves characters 127-159 explicitly undefined
and not usable for printable characters, Windows decided to put some
stuff there that's not in the ISO code, such as curly quotes and real
dashes. Character 151 is, in fact, an em dash. Type Alt-0151 and
you'll see. But since it's not defined in ISO, it won't appear in X
fonts, and so you won't see that dash on a Linux box. The Mac uses
another set entirely, so 151 is a o-acute and 249 is breve accent.
To be in strict compliance with *ML standards, you can either specify
which character set is used in you HTML DOCTYPE header, or you can
just use plain old 7-bit ASCII and encode the specials with named
character entity ("&") references. Numerical references are
theoretically standard as well, but officially they reference into 16-
bit Unicode codes (the first 256 of which are the same as ISO-8859-
1), and no browser I know will correctly display an em dash, for
example, whose code is in the 2000s, but many will display the
"mdash" named reference correctly, even displaying "--" if the local
font doesn't have it.
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