Why is usage of the downloadURL & updateURL keys called unusual and how do they work?
<p>I was reading <a href="https://wiki.greasespot.net/Metadata_Block" rel="noreferrer">GM's wiki</a> to determine the difference between <code>@downloadURL</code> &amp; <code>@updateURL</code> (which I didn't). But what confused me even more that both are unadvised:</p>

<blockquote>
  <p>It is unusual to specify this value. Most scripts should omit it.</p>
</blockquote>

<p>I'm surprised by that as it's the only way for scripts to auto-update and I don't see why these keys shouldn't be used.</p>

<p>The wiki itself is pretty lacking and no other forum sources are advised, so I have to ask here. Also would appreciate more detailed info on these keys.</p>