For the most part, what you type on the keyboard is what you see on the screen. Most fonts also have extra characters, which are not shown on the keyboard. You can enter these characters by using the [Alt] key in combination with the numeric keypad. For example, in many ANSI fonts, [Alt]+0240 = ð, a character which you won't find on too many North American keyboards.
There are types of different character sets too. The three that are important when using Keystroke are:
ASCII- ASCII stands for American Standard Code for Information Interchange. It's an old standard, with roots going back to the pre-computer days of radio tele-type (RTTY) communications, and it's pretty basic. Characters are encoded using 7 bits (ones and zeroes), which allows a total of 128 characters. That's enough for standard U.S. English upper and lower-case letters and punctuation, numbers, and some non-printing control characters (i.e., carriage-return, line-feed, etc.). Other character sets are larger, but include the ASCII characters.
ANSI- ANSI stands for American National Standards Institute. As the name implies, it's another standard, like ASCII. ANSI is encoded using 8 bits, however, which allows 256 characters. The lower half (0 through 127), is the same as the standard ASCII character set. The upper half (128 through 255) contains special accented characters and punctuation peculiar to a specific set of languages, along with a variety of publishing, monetary, and miscellaneous symbols. Most Windows fonts use ANSI characters. For English-language versions of Windows, the upper ANSI characters include punctuation and accented characters for most Western European languages.
OEM- OEM stands for Original Equipment Manufacturer. Back in the days before Windows, OEM fonts allowed MS-DOS programs to display line-drawing graphics characters properly on different manufacturers' computer systems. Windows-based applications generally don't need to use OEM fonts, but Windows still uses them for displaying DOS-based programs, as well as for some system-related functions. OEM fonts are 8-bit, like ANSI fonts, and include the standard ASCII characters. The special text characters in the upper half of each OEM font may vary, because they are not standardized, but they should all include the same MS-DOS line-draw graphics characters. Keystroke uses these graphics characters, so if font is assigned to Keystroke in the WS#.INI file, it should be one that has an OEM character-set version. Many releases of Windows include OEM character-set versions of both Courier New and Lucida Console, and will correctly display the line-draw graphics characters if either of those fonts are used.
If the Windows Character mapping utility is installed on the computer, it can be used to view the fonts that are currently available.
See:
Custom Fonts with Keystroke
Font Names
Fonts with Fixed Character Spacing