The base resource in SLADE 3 is the archive that contains all the basic game data. In practice, this will usually correspond to an IWAD such as doom2.wad. SLADE will always load the base resource archive at startup, but keep it in the background (without opening an editing tab for it).

Important things that the base resource archive contains include:

• The palette, usually as an entry named PLAYPAL.
• Texture definitions, which can be imported when creating texture definition lumps.
• Flats, textures, and sprites shown in the Map Editor.

To set up the base resource archive, go to Edit→Preferences→Editing→Base Resource Archives. You can also use the shortcuts Edit→Set Base Resource Archive, or click on the blue cog button on the toolbar, next to the Base Resource drop-down list.

Click on the "Add Archive" button to add new archives to the list. Although you should generally use an IWAD as your base resource, it is possible to select any kind of archive, even archives that are not in the WAD format. Add any appropriate file to the list of possible base resource archives.

You can now use the Base Resource drop-down list on the menu to quickly switch to any of the archives you have added to the list. Doing so will unload the current base resource, and instead load the new choice.

In some cases (such as for example working on a standalone TC), you may want to leave the base resource to the default choice of "<none>". When doing so, all needed resources will need to be provided by the archives you are currently editing. For example, graphics in the Doom format (which need a palette but do not contain palette data) will appear in greyscale because of the lack of palette information from the base resource archive, unless your archive does contain its own palette (or you chose a specific palette from the Palette drop-down list instead of the "Existing/Global" default choice).