title: Why is the dollar sign no longer "intended for use only in mechanically generated code?"
body: <p>In <a href="http://www.ecma-international.org/publications/files/ECMA-ST-ARCH/ECMA-262,%203rd%20edition,%20December%201999.pdf" rel="nofollow noreferrer">ECMA-262, 3rd edition<sup>[PDF]</sup></a>, under section 7.6 ("Identifiers," page 26), we see the following note:</p>
  
  <blockquote>
    <p>The dollar sign is intended for use only in mechanically generated code.</p>
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  <p>That seems reasonable. Many languages commonly used for generating or embedding JavaScript hold a special meaning for <code>$</code>, and using it in JavaScript identifiers within those languages leads to <a href="https://stackoverflow.com/questions/16453426/48-appearing-in-javascript-code-instead-of">unexpected behavior</a>.</p>
  
  <p>The "mechanically generated clause" appeared in edition 2. In edition 1, it was not present. As of edition 5, it disappears again without explanation, and it remains <a href="http://people.mozilla.org/~jorendorff/es6-draft.html#sec-7.6" rel="nofollow noreferrer">absent</a> from the working draft of the 6th edition.</p>
  
  <p>If I had to guess, I'd assume it was originally omitted because the potential pitfalls hadn't been considered, and was then added in the next edition when it became clear that it was causing problems. I can't think of a good reason for removing it again in edition 5, though.</p>
  
  <p>Is there any explanation for the inclusion and subsequent removal of the "mechanically generated clause" from the specification (a "paper trail" from mailing lists, newsgroups, or elsewhere)? I can't find this documented anywhere.</p>
  
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  <p>As a side question, can anyone explain the rationale behind <a href="http://people.mozilla.org/~jorendorff/es6-draft.html#sec-7.6" rel="nofollow noreferrer">including zero-width characters</a> in the edition 6 draft? This seems like it will cause even more trouble, given that you can't see those characters at all, and I can't think of any reason you'd want those characters in an identifier.</p>
  
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  <p><strong>Update:</strong> The initial inclusion of the "mechanically generated code" note and the inclusion of zero-width characters are explained in codewaggle's answer below. The only thing remaining to be answered is the primary focus of this question, the <em>removal</em> of the "mechanically generated code" note.</p>