+=head2 Floating Point Considerations
+
+Prior to 5.8.0, Perl simply accepted the default floating point options of the
+C compiler, namely representing doubles with D_FLOAT on VAX and G_FLOAT on
+Alpha. Single precision floating point values are represented in F_FLOAT
+format when either D_FLOAT or G_FLOAT is in use for doubles. Beginning with
+5.8.0, Alpha builds now use IEEE floating point formats by default, which in
+VMS parlance are S_FLOAT for singles and T_FLOAT for doubles. IEEE is not
+available on VAX, so F_FLOAT and D_FLOAT remain the defaults for singles and
+doubles respectively. Itanium builds have always used IEEE by default. The
+available non-default options are G_FLOAT on VAX and D_FLOAT or G_FLOAT on
+Alpha or Itanium.
+
+The use of IEEE on Alpha or Itanium introduces NaN, infinity, and denormalization
+capabilities not available with D_FLOAT and G_FLOAT. When using one of those
+non-IEEE formats, silent underflow and overflow are emulated in the conversion
+of strings to numbers, but it is preferable to get the real thing by using
+IEEE where possible.
+
+Regardless of what floating point format you consider preferable, be aware
+that the choice may have an impact on compatibility with external libraries,
+such as database interfaces, and with existing data, such as data created with
+the C<pack> function and written to disk, or data stored via the Storable
+extension. For example, a C<pack("d", $foo)")> will create a D_FLOAT,
+G_FLOAT, or T_FLOAT depending on what your Perl was configured with. When
+written to disk, the value can only be retrieved later by a Perl configured
+with the same floating point option that was in effect when it was created.
+
+To obtain a non-IEEE build on Alpha or Itanium, simply answer no to the
+"Use IEEE math?" question during the configuration. To obtain an option
+different from the C compiler default on any platform, put in the option that
+you want in answer to the "Any additional cc flags?" question. For example, to
+obtain a G_FLOAT build on VAX, put in C</FLOAT=G_FLOAT>.