If you edit files in different human languages, you will most likely be familiar with the concept of a "character encoding". The simplest explanation of this is that there are several ways in which a character can be stored on disk; different programs must be set to the same encoding to be able to exchange text. The current buffer's encoding is shown in the status bar.
jEdit can use any encoding supported by the Java platform. The default encoding, used to load and save files for which no other encoding is specified, can be set in the Loading and Saving pane of the Utilities>Global Options dialog box; see the section called "The Global Options Dialog Box". The setting is presented as an editable combo box; the combo box contains a few of the more frequently used encodings, but the Java platform defines practically hundreds more you can use.
Unfortunately, there is no way to obtain a list of all supported encodings in Java, and the set is constantly changing with each Java version. So to play it safe, jEdit has a few pre-defined defaults, but allows you to use any other supported encoding, assuming you know its name.
Unless you change the default encoding, jEdit will use your operating system's native default; MacRoman on the MacOS, Cp1252 on Windows, and 8859_1 on Unix.
The File>Open With Encoding lets you open a file with an encoding other than the default. The menu contains a set of items, one for each common encoding, along with System Default and jEdit Default commands. Invoking a menu item displays the usual file dialog box, and opens the selected file with the chosen encoding.
The Open With Other Encoding command in the same menu lets you enter an arbitrary encoding name, assuming it is supported by your Java implementation.
Once a file has been opened, the encoding to use when saving it can be set in the Utilities>Buffer Options dialog box.
If a file is opened without an explicit encoding specified and it appears in the recent file list, jEdit will use the encoding last used when working with that file; otherwise the default encoding will be used.
The most frequently-used character encoding is ASCII, or "American Standard Code for Information Interchange". ASCII encodes Latin letters used in English, in addition to numbers and a range of punctuation characters. The ASCII character set consists of 127 characters, and it is unsuitable for anything but English text (and other file types which only use English characters, like most program source). jEdit will load and save files as ASCII if the ASCII encoding is used.
Because ASCII is unsuitable for international use, most operating systems use an 8-bit extension of ASCII, with the first 127 characters remaining the same, and the rest used to encode accents, umlauts, and various less frequently used typographical marks. Unfortunately, the three major operating systems all extend ASCII in a different way. Files written by Macintosh programs can be read using the MacRoman encoding; Windows text files are usually stored as Cp1252. In the Unix world, the 8859_1 (otherwise known as Latin1) character encoding has found widespread usage.
Windows users are accustomed to dealing with files in a wide range of character sets, known as code pages. Java supports a large number of code pages; the encoding name consists of the text "Cp", followed by a number.
Raw Unicode files are quite rare, but can be read and written with the Unicode encoding. One reason raw Unicode has not found widespread usage for storing files on disk is that each character takes up 16 bits. Most other character sets devote 8 bits per character, which saves space. The UTF8 encoding encodes frequently-used Unicode characters as 8 bits, with less-frequent ones stretching up to 24 bits. This saves space but allows the full range of Unicode characters to be represented.
Many common cross-platform international character sets are supported; KOI8_R for Russian text, Big5 and GBK for Chinese, and SJIS for Japanese.