That just means the initial prompt says something like, "You are an expert Wikipedia research assistant. You can only reference material found on Wikipedia. Try

That just means the initial prompt says something like, "You are an expert Wikipedia research assistant. You can only reference material found on Wikipedia. Try your best to help the user by giving summaries of Wikipedia content. Do not reference material from other websites!" The model is still trained on a broad corpus like ChatGPT3, i.e., the Internet. The corpus of Wikipedia alone probably isn't enough training data.