title: In cache-Control header field why does it named as "directives"?
body: <p>I wanted to know why standard HTTP/1.1 header fields define <strong>Cache-Control</strong> as <strong>directives</strong> ?
  and other header fields not marked as same.</p>
  
  <p>I went though the all standard HTTP/1.1 header fields [<a href="https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html]" rel="nofollow noreferrer">https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html]</a> definition it only apply with Cache-Control general-header field except <strong>Pragma</strong> general-header field where I also does not have idea.</p>