From the Introduction ... 'The Fire and fuels Extension (FFE) has been developed for 18 of the Forest Vegetation Simulator (FVS) variants: Northern Idaho, Kookantl, Central Rockies, Utah, Eastern Montana, Western Sierra, Blue Mountains, Eastern Cascades, Central Idaho, Tetons, Southern Oregon/Northern California, Klamath Mountains, Inland California and Southern Cascades, Inland Empire, Southern, Pacific Northwest Coast Westside Cascades, and Lake States. Northern Idaho was the first variant developed and is considered the 'base variant' as described in the FFE Model Description and User's Guide. The Model Description document provides an in-depth look into the logic and parameters of that variant. As new variants have been developed, logic and parameter modifications were made to the NI variant in order to model fire effects in the regions covered by the new variants. The modifications were based on workshops and consultations with scientists and other fire experts familiar with each variant's region. Many revisions were based on 'expert knowledge' and unpublished information. References are included for modifications based on published information.The user can modefy many of the model processes, for instance snag dynamics. Some of the keywords are identified in this document; however, all of the user keywords are described in the FFE Model Description (RMRS-GTR-116, chapter 2).'