Holy cow, I wrote a book!
asks why Wordpad has three formats,
Text Document - MS-DOS Format,
Unicode Text Document.
at least one redundant?"
Recall that in Windows, three code pages have special status.
Three text file formats.
As you might have guessed by now, the three text file formats
correspond to the three special code pages.
Now it's just a matter of deciding which one matches with which.
The easiest one is the Unicode one;
it seems clear that Unicode Text Document matches
Okay, we now have to figure out how Text Document and
Text Document - MS-DOS Format map to
CP_ACP and CP_OEM.
But another piece of the puzzle is pretty clear,
MS-DOS used the so-called OEM code page.
Therefore, by process of elimination,
Text Document corresponds to CP_ACP.
Now that we have puzzled out what the three text formats correspond to,
we can address the question
"Isn't at least one redundant?"
Michael Kaplan explained that
ACP and OEM are (usually) different.
And neither is the same as Unicode.
So in fact all three are (usually) different.
In the United States, the so-called ANSI code page is
code page 1252,
the so-called OEM code page is
code page 437,
and Unicode is code page 1200.
Here's the string résumé expressed in each
of the three encodings.
Three encodings, three different files.