The file extension ABK marks files of the word processing Write documents of the Ability Office in the native, proprietary format of the application. These files include text, formatting, fonts, graphics, and images.
They contain a slightly older version of the current document. Write can open these files directly.
Write is part of the Ability Office and not available separately. The software package is available in different editions and was also licensed by other manufacturers. These sell the products under their own name and with a partially adapted interface.