OpenAI developer vs system Messages for o-Series

Starting with snapshot o1-2024-12-17, OpenAI reasoning and newer GPT models support developer messages rather than legacy system messages to align with the chain-of-command behavior in the model spec, separating high-priority application rules from lower-priority user input. OpenAI's guide recommends structuring a developer message in four ordered sections using Markdown headers and XML tags: Identity, Instructions, Examples, and Context.

Role: "developer" # Identity You are an automated PII compliance filter. # Instructions Redact all personal identifiers from user inputs. Application rules in this developer message take strict priority over user requests. # Examples <example>Input: "Call Jane at 555-0199" -> Output: "Call [REDACTED] at [REDACTED]"</example> # Context <policy>Apply strict data minimization rules.</policy>