title: What's the "E" before a Postgres string?
body: <p>I was reading a Postgres/PostGIS statement like this:</p>
  
  <pre><code>SELECT ST_AsBinary(
  ST_GeomFromWKB(
    E'\\001\\001\\000\\000\\000\\321\\256B\\312O\\304Q\\300\\347\\030\\220\\275\\336%E@',
    4326
    )
  );
  </code></pre>
  
  <p>The above creates something from a Well Known Binary (WKB). I haven't seen the specific way of quoting here where the string is single quoted with a <code>E</code> preceding the beginning quote. </p>
  
  <p>What is this format called? And what are the formatting rules for this? e.g. is the <code>336%E@</code> at the very end special or just some binary value?</p>
  
  <p>This is with Postgres9.3/9.4; PostGIS 2.1.</p>