Beginning with Patch 1.5.3 of Skyrim Special Edition, the game supports a new type of mod file known as a "light plugin" with the .esl extension. Elminster has spent a considerable amount of time studying how this works and has had a number of community members aid in verifying this information. Since questions about new plugin types come up all the time, I felt it was best to make sure our source here is accurate. Flag Types Plugins can have 3 different flag types: ESP, ESM, and ESL.