t;-hex</dt>
<dd>
<p>are the 40-hexdigit SHA-1 hashes,</p>
</dd>
<dt class="hdlist1">&lt;old|new&gt;-mode</dt>
<dd>
<p>are the octal representation of the file modes.</p>
<div class="paragraph">
<p>The file parameters can point at the user&#8217;s working file
(e.g. <code>new-file</code> in "git-diff-files"), <code>/dev/null</code> (e.g. <code>old-file</code>
when a new file is added), or a temporary file (e.g. <code>old-file</code> in the
index).  <code>GIT_EXTERNAL_DIFF</code> should not worry about unlink