{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://openvisual.org/schema/vertigo/1.0",
  "title": "OVS: Vertigo (Visual Sway)",
  "description": "Visual manifestation of vertigo and postural instability: the whole visual field appears to sway, rock or rotate slowly. Distinct from oscillopsia (fast vibration) and peripheral tremor (localized). HPO Vertigo (HP:0002321) is frequent and Postural instability (HP:0002172) occasional in VSS. `severity` is the sway amplitude (1 = about 4° rotation).",
  "allOf": [
    {
      "$ref": "https://openvisual.org/schema/symptom-base/1.0"
    },
    {
      "type": "object",
      "properties": {
        "ovs_type": {
          "const": "ovs:vertigo"
        },
        "sway_frequency_hz": {
          "type": "number",
          "minimum": 0,
          "description": "Dominant sway frequency in Hz (typically 0.05–1)"
        }
      }
    }
  ]
}