<ul>
-<li>Double rounding (x87 issue):
+<li>Double rounding:
<p>
If a value rounded twice the result can be different
than rounding just once.
(afaik freebsd and openbsd use double precision by default)
<p>
So x = a+b may give different results depending on
-the fpu setting.
+the x87 fpu precision setting.
(only happens in round to nearest rounding mode,
but that's the most common one)
<p>
+(double rounding can happen with float vs double as well)
+<p>
C99 annex F prohibits double rounding,
but that's non-normative.