-* Dec C issues
-
-Note to DECC users: Some early versions (pre-5.2, some pre-4. If you're Dec
-C 5.x or higher, with current patches if any, you're fine) of the DECCRTL
-contained a few bugs which affect Perl performance:
- - Newlines are lost on I/O through pipes, causing lines to run together.
- This shows up as RMS RTB errors when reading from a pipe. You can
- work around this by having one process write data to a file, and
- then having the other read the file, instead of the pipe. This is
- fixed in version 4 of DECC.
- - The modf() routine returns a non-integral value for some values above
- INT_MAX; the Perl "int" operator will return a non-integral value in
- these cases. This is fixed in version 4 of DECC.
- - On the AXP, if SYSNAM privilege is enabled, the CRTL chdir() routine
- changes the process default device and directory permanently, even
- though the call specified that the change should not persist after
- Perl exited. This is fixed by DEC CSC patch AXPACRT04_061.
-
-* Mailing Lists
-
-There are several mailing lists available to the Perl porter. For VMS
+=head2 GNU issues with Perl on VMS
+
+It has been a while since the GNU utilities such as GCC or GNU make
+were used to build perl on VMS. Hence they may require a great deal
+of source code modification to work again.
+
+ http://www.progis.de/
+
+=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, simply answer no to the "Use IEEE math?"
+question during the configuration. To obtain an option different from the C
+compiler default on either VAX or Alpha, 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>.
+
+=head1 Mailing Lists
+
+There are several mailing lists available to the Perl porter. For VMS