Okteta is a simple editor for the raw data of files. This type of program is also called hex editor or binary editor.
This repository contains a set of definitions that make analisis of windows binary files in COFF/PE/PE+ format more convenient in okteta. It is not a stand alone application, just some data files that can only be used in conjunction with okteta.
Check the section on the structures tool in the okteta manual for details on how to install this.