//any

Any has two uses: either it accepts absolutely any value (including the lack of a value) or it accepts a value accepted by any of a list of alternatives. These two forms look like this:

Match absolutely anything:

{ "type": "//any" }

Match either no value or an integer from 1 to 6:

{
    "type": "//any",
    "of": [
      "//nil",
      { "type": "//int", "range": { "min": 1, "max": 6 } }
    ]
}

"of" is the only permissible for //any, and if given it must be a list of one or more valid schema definitions.

/.meta/any, the schema for //any definitions:

{
  "type": "//rec",
  "required": {
    "type": { "type": "//str", "value": "//any" },
  },
  "optional": {
    "of": {
      "type": "/arr",
      "contents": "/.meta/schema",
      "length": { "min": 1 },
    }
  }
}