Using Module Extensions in VASSAL 3.1.x and later

• Extensions add capability to a game in the form of additional counters, maps, charts, help files, or other items that are not typically needed in the basic version of the game. Although extensions add material, they cannot take material away.
• Some games use extensions in series; they build upon the base module where the additions are always beneficial. For example, Crescendo of Doom uses almost all components found in VSQL (module for Squad Leader and Cross of Iron). By enabling COD  extension, one can play at the COD level. Those who only want to play at the SQL/COI level, simple do not install the COD extension. Similarly those playing at the GI: Anvil of Victory level, will install both the GIA and COD extensions as typically COD capability is needed as a prerequisite to GIA.
• Other games such as Luftwaffe use extensions in series. The Basic game has a specific OOB chart and scenario start file. These are not used when playing the Tournament Game. Similarly, the Tournament Game OOB is used when playing the Advanced game. Additionally, the Basic and Advanced games have different published variants that may be in use. The Aerial Combat Chart is replaced when using the Tactical game, which also used a 2d6 instead of a 1d6. The Tactical game may be used in parallel to any version of the Basic Games or Advanced Games. Lastly, rather than using the 'Classic' counter images which match the published 1971 game, some player may wish to use the graphically 'Enhanced' counter set. Although the Classic counters cannot be removed from the counter menu the Enhanced counter set will not be visible unless that enhancement is use. Similarly, the scenario files using the Enhanced counter sets will be only visible when using the Enhances.mdx extension.
• To utilize extensions, an extension folder must exist in the same level of the file structure as the module. It is CRITICAL that the extension folder follow a specific naming convention for Vassal to recognize and load the extensions properly when loading the module. If the module is named 'XXX.vmod', the extension folder must be named 'XXX_ext'. The extension files themselves may be named anything but must end with NO extension.
• Any extension found in the properly named extension folder will be loaded when the main module (xxx.vmod) is loaded. It can also be activated when the module is running by using the "Add Extension" command in the menu.
• To disable an extension, remove it directly from the extension folder and place it in a different folder such as ’Disabled Extensions' or use the "Remove Extension" command while running the main .vmod program.
• Recommended file structure is to have a folder indicating the module version, for example: LFW20 for Luftwaffe version 2.0. Inside that is the main LFW.vmod file, LFW_ext folder, and Disabled Extensions folder.

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