Birdperson

Hello. I downloaded server source to learn some hard facts about the odds and other inner workings of the game. I'm not a C++ programmer(I'm from Java), but i can read he C syntax just fine. However, I encountered a problem. In the code a class called LPITEM is often used. I've been trying to search for its implementation but after a lot of searching I couldn't find it anywhere. Sorry if this is a noob question, but can you tell me where it is?