title: Why is CHAR_BIT usually 8?
body: <p>According to <code>N4140</code>(C++11 working draft):</p>
  
  <blockquote>
    <p>The fundamental storage unit in the C ++ memory model is the byte. A byte is at least large enough to contain any member of the basic execution character set and the eight-bit code units of the Unicode UTF-8 encoding form and is composed of a contiguous sequence of bits, the number of which is implementation-defined. (§6.6.1-1; p.48)</p>
  </blockquote>
  
  <p>I think 8 bits are needed only to contain all members of "the eight-bit code units of the Unicode UTF-8 encoding form". Aren't more bits needed also to contain all members of "the basic execution character set"? Why can <code>CHAR_BIT</code> be 8 in many implementations?</p>