title: Are HTTP headers (Content-Type, &c.) case-sensitive?
body: <p>Perhaps I'm skimming too fast, but couldn't find this specifically documented. In my particular case, I'm wondering about the "Content-Type" header, but I'm assuming the same rules would apply to other standard headers. </p>
  
  <p><strong>Are these case sensitive, and if so: Is it <code>Content-Type</code> or <code>Content-type</code>?</strong></p>
  
  <p>Is there a proper place to reference these?</p>