[1][2] A document writer application may support a multitude of files, ranging from simple text files that only store characters and not font faces or sizes, to complex documents containing text effects and images.
However, when these text files or documents are opened, they are not necessarily edited in their original format.
In some cases, applications may be able to open (import) files, but not save (export) them in the same format.
This may be due to licensing issues, or simply because the feature has not been implemented in the application's programming yet.
For example, Microsoft Office Word 2003 is able to open Windows Write (*.wri) files, but cannot save them.