title: Rationale for 509 minimum character limit
body: <p>I've seen a lot of the minimal requirements that an ANSI C compiler must support like 31 arguments to a function, and most of the numbers seem to make some kind of sense.</p>
  
  <p>However, I cannot see the reasoning for supporting at least 509 characters in a source line.  511 or 512 would make more sense, but 509 seems kind of arbitrary.</p>
  
  <p>What is the reason for this number?</p>