Mention the possibility of fp rounding modes' effects.

diff --git a/pod/perldata.pod b/pod/perldata.pod
index 52921ca..c490b63 100644 (file)
--- a/pod/perldata.pod
+++ b/pod/perldata.pod
@@ -432,7 +432,10 @@ but it must be followed by C<p>, an optional sign, and a power of two.
 The format is useful for accurately presenting floating point values,
 avoiding conversions to or from decimal floating point, and therefore
 avoiding possible loss in precision.  Notice that while most current
-platforms use the 64-bit IEEE 754 floating point, not all do.
+platforms use the 64-bit IEEE 754 floating point, not all do.  Another
+potential source of (low-order) differences are the floating point
+rounding modes, which can differ between CPUs, operating systems,
+and compilers, and which Perl doesn't control.
 
 You can also embed newlines directly in your strings, i.e., they can end
 on a different line than they begin.  This is nice, but if you forget