It is a way to interact with their chat api: https://platform.openai.com/docs/guides/chat/introduction

It already exists, but according to their docs current chatGPT "does not always pay strong attention to system messages. Future models will be trained to pay stronger attention to system messages"

Instead of one large prompt there's now 'system', 'user', and 'assistant' prompts which are meant to be given specific instructions each. So you could tell the system prompt that it's a librarian and ask the message prompt what date a book was published.

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