While plain-text is probably the simplest and most interchangeable file format in the computer world, there is still variation in what plain-text means from system to system. Plain-text files can differ in character encoding, line termination, and wrapping.

Character encoding differences are the most obvious and pose the most challenge to portability. NEdit-ng cannot currently display Unicode (UTF-8) text files correctly, nor any multi-byte character set. Some modern programming languages such as JavaScript, Raku and Apple's Swift can accept UTF-8 encoded source code; these should not be written or edited using current versions of NEdit-ng.

The primary difference between an MS-DOS format file and a Unix format file is how the lines are terminated. Unix uses a single newline character. MS-DOS uses a carriage-return and a newline. NEdit-ng can read and write both file formats, but internally, it uses the single character Unix standard. NEdit-ng auto-detects MS-DOS format files based on the line termination at the start of the file. Files are judged to be MS-DOS format if all of the first five line terminators, within a maximum range, are MS-DOS style. To change the format in which NEdit-ng writes a file from MS-DOS to Unix or visa versa, use the File → Save As... command and check or un-check the MS-DOS Format button.

Wrapping within text files can vary among individual users, as well as from system to system. Both Windows and macOS make frequent use of plain text files with no implicit right margin. In these files, wrapping is determined by the tool which displays them. Files of this style also exist on Unix systems, despite the fact that they are not supported by all Unix utilities. To display this kind of file properly in NEdit-ng, you have to select the continuous wrap mode (Preferences → Wrap → Continuous). Wrapping modes are discussed in Preferences and Shifting and Filling.

The last and most minute of format differences is the terminating newline. Some programs expect a final terminating newline on all files they read and may fail in various ways on files which do not have it. Some text editors such as Vi enforce the terminating newline on all files that they write; Emacs does not enforce this rule. Users are divided on which is best. NEdit-ng makes the final terminating newline optional (Preferences → Default Settings → Terminate with Line Break on Save).