gistfile1.js

schema = {
  "properties": {
    "topPane": {
      "$ref": "paneSchema"     // referring directly by a new id, not #/paneSchema
    },
    "bottomPane": {
      "$ref": "paneSchema"
    }
  },
  "paneSchema": {
    "properties": {
      "height": {
        "type": "number"
      }
    }
  }
};

doc = {
  "topPane": {
    "height": 10
  },
  "bottomPane": {
    "height": "not-a-number"
  }
};

env = JSV.createEnvironment();

env.createSchema(schema.paneSchema, schema, "paneSchema");   // this is the key

report = env.validate(doc, schema);