title: JSON schema - possible to reference multiple schemas from one object?
body: <p>Below is an extract from my JSON schema.</p>
  
  <pre><code>{
      "$schema": "http://json-schema.org/draft-04/schema#",
      "type": "object",
      "properties": {
          "images": {
              "type": "array",
              "items": { "$ref": "#/definitions/bits" },
          }
      },
      "definitions": {
          "identifier": {
              "type": "string"
          },
          "bits": {
              "type": "integer",
              "enum": [
                  8,
                  16,
                  32
              ]
          }
      }
  }
  </code></pre>
  
  <p>As specified, I believe an array of images, where each element consists of a string identifier and an integer whose value can be 8, 16 or 32, would be considered valid JSON data.</p>
  
  <p>This is fine for some of my JSON data. </p>
  
  <p>But what if I want to further constrain the schema such that the integer value can only be 32? How would I do that while still allowing some JSON data to be valid against the original schema? </p>
  
  <p>Is it possible, for example, to reference two schemas in one object, E.g. something like:</p>
  
  <pre><code>items": { "$ref": "#/definitions/bits" AND "$ref": "#/definitions/otherSchema"}
  </code></pre>