The tool is intended to help Dungeon Masters (and to a limited degree players) prepare and keep track of the game. In it final realization, it should be able to take care of most of the data of a campaign, including items, monsters, and npcs, but also regions, shops, taverns, gods and events of a campaign. In it's current state the tool only provides detailed information about D&D products and items.
jDMA is based on the Dungeons & Dragons rules (version 3.5), with some simplification or clarifications made where necessary.