title: SP Char in HTTP Headers?
body: <p>I've been examining HTTP 1.1 specifications and well I saw something like this:</p>
  
  <blockquote>
    <p>Request-Line   = Method SP Request-URI SP HTTP-Version CRLF</p>
  </blockquote>
  
  <p>I know what this Request-Line stands for but I wonder what <code>SP</code> stands for? What kind of character is that?</p>
  
  <p>Link: <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.1" rel="noreferrer">http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html#sec5.1</a></p>
  
  <p><strong>Edit:</strong></p>
  
  <p>In the hope of helping people who visit this page somehow, I found this complete set of codes in the pages provided by the answering people:</p>
  
  <pre><code>OCTET          = &lt;any 8-bit sequence of data&gt;
  CHAR           = &lt;any US-ASCII character (octets 0 - 127)&gt;
  UPALPHA        = &lt;any US-ASCII uppercase letter "A".."Z"&gt;
  LOALPHA        = &lt;any US-ASCII lowercase letter "a".."z"&gt;
  ALPHA          = UPALPHA | LOALPHA
  DIGIT          = &lt;any US-ASCII digit "0".."9"&gt;
  CTL            = &lt;any US-ASCII control character
                   (octets 0 - 31) and DEL (127)&gt;
  CR             = &lt;US-ASCII CR, carriage return (13)&gt;
  LF             = &lt;US-ASCII LF, linefeed (10)&gt;
  SP             = &lt;US-ASCII SP, space (32)&gt;
  HT             = &lt;US-ASCII HT, horizontal-tab (9)&gt;
  &lt;"&gt;            = &lt;US-ASCII double-quote mark (34)&gt;
  </code></pre>
  
  <p>They become important as they're being used buy the specifications to explain the formats of the headers and many other things as well. </p>