> ## Documentation Index > Fetch the complete documentation index at: https://openrouter.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # ReasoningMode Selects the reasoning mode. `standard` is the default; `pro` engages deeper reasoning on models that support it, billed at standard token rates. Only supported by OpenAI GPT-5.6 and newer. ## Example Usage ```typescript theme={null} import { ReasoningMode } from "@openrouter/sdk/models"; let value: ReasoningMode = "standard"; // Open enum: unrecognized values are captured as Unrecognized ``` ## Values ```typescript theme={null} "standard" | "pro" | Unrecognized ```