> ## Documentation Index > Fetch the complete documentation index at: https://medlogprotocol.ai/llms.txt > Use this file to discover all available pages before exploring further. # Record schema overview > Each MedLog record corresponds to one model invocation and contains nine fields. The MedLog protocol captures AI use at the level of an inference call. It applies to simple "prompt to model to response" systems as well as multi-stage workflows that use retrieval, tools, rubric-based evaluation, or agentic orchestration. MedLog treats each model invocation as an event and allows events to be linked within the same run or episode. Each MedLog record corresponds to **one model invocation** and contains the following nine fields. ## Fields available at invocation Provenance information, execution context, and system metadata available at inference time. Stable identifiers of the AI model and version, with references to its model card and data sheet. The technical process, service, or workflow that invokes the model call. A reference to the entity about which the model produces output. The input data provided to the model. ## Fields appended later Artifacts generated during inference for technical researchers and MLOps engineers. The outputs intended for human users. Records of clinical actions or patient outcomes linked to the model recommendation. Any feedback provided by users, whether structured ratings or free-text comments. This documentation describes the conceptual nine-field model from the MedLog protocol. The [API reference](/api-reference/overview) defines the concrete event payloads a collector accepts. See the [annotated example record](/specification/example-record) for how the two relate.