difference</b>: two compatible cdata pointers/arrays
can be subtracted. The result is the difference between their
addresses, divided by the element size in bytes. An error is raised if
the element size is undefined or zero.</li>

<li><b>64&nbsp;bit integer arithmetic</b>: the standard arithmetic
operators (<tt>+&nbsp;-&nbsp;*&nbsp;/&nbsp;%&nbsp;^</tt> and unary
minus) can be applied to two cdata numbers, or a cdata number and a
Lua number. If one of them is an <tt>uint64_t</tt>, the other side is
converted