{
  "description": "The Elmer ``Constants`` block: each constant is an optional field carrying its sif keyword; a physics sets only the constants it needs, and an unset one is omitted.",
  "properties": {
    "extra_keywords": {
      "additionalProperties": {
        "anyOf": [
          {
            "type": "string"
          },
          {
            "type": "integer"
          },
          {
            "type": "number"
          },
          {
            "type": "boolean"
          }
        ]
      },
      "description": "Escape hatch: verbatim sif keyword/value pairs merged (last, so they win) into [`to_elmer`][] \u2014 any Elmer\nkeyword the typed fields don't model yet stays authorable without subclassing.",
      "title": "Extra Keywords",
      "type": "object"
    },
    "permeability_of_vacuum": {
      "anyOf": [
        {
          "type": "number"
        },
        {
          "type": "null"
        }
      ],
      "default": null,
      "description": "`\u03bc\u2080` `[H/m]`: Needed by the magnetostatic solver.",
      "title": "Permeability Of Vacuum"
    },
    "permittivity_of_vacuum": {
      "anyOf": [
        {
          "type": "number"
        },
        {
          "type": "null"
        }
      ],
      "default": null,
      "description": "`\u03b5\u2080` `[F/m]`: Needed by the electrostatic solver.",
      "title": "Permittivity Of Vacuum"
    },
    "stefan_boltzmann": {
      "anyOf": [
        {
          "type": "number"
        },
        {
          "type": "null"
        }
      ],
      "default": null,
      "description": "`\u03c3_SB` `[W/(m\u00b2\u00b7K\u2074)]`: Needed for thermal radiation.",
      "title": "Stefan Boltzmann"
    }
  },
  "title": "Constants",
  "type": "object"
}