ASCII is the character set used under DOS and ANSI is used under Windows. If you don't use extended characters (such as äèüö etc.), there is no difference between the two. However, if you create a document under DOS that uses extended characters and want to display them correctly under Windows, the text must be "translated" from ASCII to ANSI in order to display the accented characters correctly. Also, if you create a Windows text document (ANSI) and want to use it in a DOS application, it must be converted to ASCII if it contains extended characters.
This editor has a built-in filter that makes it easy to edit files of either format. Note, however, that a conversion between the two formats may not always translate all characters correctly. There are mainly two reasons for this: 1) the extended ANSI characters are not necessarily supported by all font types; 2) DOS has many different character sets available, which means that extended characters are often quite different from one set to the other. The filter used in this program is based on ASCII 850 Multilingual (Latin I).
By default, the file filter list has an item for opening and saving DOS Ascii files. Since you can change the order of the filters and edit them, the program just checks for the word ASCII (case does not matter) in the selected filter when you use the file dialog box. If it finds the word ASCII, it assumes that you want to open or save a file in the DOS Ascii format. So if you want to change the default file filters but also want to use ASCII documents, remember to put the word ASCII in the description part of at least one of the filter items! You can edit the filters by opening the Options dialog box and selecting the File Filters tab.
If you convert a document from ASCII to ANSI and want it to keep its ANSI format permanently, you will have to open the Document Properties dialog box and uncheck the Dos ASCII option.