t;x, y&gt;"   is a sign that denotes &lt;x, y&gt;    (in the real world).
&gt; &gt;  "R"        is a sign that denotes {&lt;x, y&gt; : &lt;x, y&gt; in R} (ITRW).
&gt; &gt; '"Matthew"' is a sign that denotes "Matthew" (in the real world).
&gt; &gt; '"x"'       is a sign that denotes "x"       (in the real world).
&gt; &gt; '"&lt;x, y&gt;"'  is a sign that denotes "&lt;x, y&gt;"  (in the real world).
&gt; &gt; '"R"'       is a sign that denotes '"R"'     (in the real world).
&gt; &gt;
&gt; &gt; ...
&gt; &gt;
