addition to the negated version of the Selector (see NotSelector
                            below), the selector expression syntax itself supports
                            negation.  The two types of negation are subtly different.
                            One negates the set of matched endpoints, the other negates
                            the whole match: \n \tSelector = \"!has(my_label)\" matches

<p>
For integer operands, the unary operators
<code>+</code>, <code>-</code>, and <code>^</code> are defined as
follows:
</p>

<pre class="grammar">
+x                          is 0 + x
-x    negation              is 0 - x
^x    bitwise complement    is m ^ x  with m = "all bits set to 1" for unsigned x
                                      and  m = -1 for signed x
</pre>