title: Can JSON schema enums be case insensitive?
body: <h1>JSON Schema enums</h1>
  
  <p><a href="http://spacetelescope.github.io/understanding-json-schema/UnderstandingJSONSchema.pdf" rel="noreferrer">JSON Schemas feature enums, which impose a constraint on the values of a string type</a>:</p>
  
  <pre><code>{
      "type": "array",
      "items": [
          {
              "type": "number"
          },
          {
              "type": "string"
          },
          {
              "type": "string",
              "enum": ["Street", "Avenue", "Boulevard"]
          },
          {
              "type": "string",
              "enum": ["NW", "NE", "SW", "SE"]
          }
      ]
  }
  </code></pre>
  
  <p>This schema validates values such as <code>[1600, "Pennsylvania", "Avenue", "NW"]</code>.</p>
  
  <h1>The problem</h1>
  
  <p>Is there an elegant way to make the <code>enum</code> case-insensitive, so that both <code>Avenue</code> and <code>avenue</code> would be accepted as the third value in the array?</p>
  
  <h1>Other possible solutions</h1>
  
  <p>I can use <code>anyOf</code> on a list of values, and validate each against a case-insensitive regex - but that's cumbersome, error-prone and inelegant.</p>