Editing

Descent Manager
A multi-function set of utilities for editing many aspects of Descent 1, 2, and 3, and FreeSpace 1 and 2.
http://descent2.com/descman/index.html

DTX
A tool to extract and replace graphics, sound and music for Descent I.
http://www.cybertrash.com/shareware/dtx/

File Type Specifications
Includes specs, editors, information, and other resources for Descent development of various data files in Descent 1 and 2.
http://descent2.com/ddn/

HAMM
A utility that allows you to edit Descent 1 and 2 HOG files.
http://members.ozemail.com.au/~prunge/