252 lines
6.1 KiB
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252 lines
6.1 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML><HEAD><TITLE>Manpage of TIFFReadRGBATile</TITLE>
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</HEAD><BODY BGCOLOR=WHITE><FONT FACE="helvetica, sans, arial">
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<H1>TIFFReadRGBATile</H1>
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Section: Misc. Reference Manual Pages (3T)<BR>Updated: December 10, 1998<BR><A HREF="#index">Index</A>
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<BR><A HREF="index.html">Return to Main Contents</A>
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<HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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TIFFReadRGBATile - read and decode an image tile into a fixed-format raster
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#include <<A HREF="file:/usr/include/tiffio.h">tiffio.h</A>></B>
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<B>#define TIFFGetR(abgr) ((abgr) & 0xff)</B>
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<B>#define TIFFGetG(abgr) (((abgr) >> 8) & 0xff)</B>
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<B>#define TIFFGetB(abgr) (((abgr) >> 16) & 0xff)</B>
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<B>#define TIFFGetA(abgr) (((abgr) >> 24) & 0xff)</B>
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<B>int TIFFReadRGBATile(TIFF* tif, uint32 x, uint32 y, uint32 * raster )</B>
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</PRE><A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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<I>TIFFReadRGBATile</I>
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reads a single tile of a tile-based image into memory, <BR>
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storing the result in the user supplied RGBA
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<I>raster</I>.
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The raster is assumed to be an array of
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width times length 32-bit entries, where width
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is the width of a tile (TIFFTAG_TILEWIDTH) and
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length is the height of a tile (TIFFTAG_TILELENGTH).
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<P>
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<P>
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The
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<I>x</I>
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and
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<I>y</I>
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values are the offsets from the top left corner to the top left corner
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of the tile to be read. They must be an exact multiple of the tile
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width and length.
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<P>
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<P>
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Note that the raster is assume to be organized such that the pixel
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at location (<I>x</I>,<I>y</I>) is <I>raster</I>[<I>y</I>*<I>width</I>+<I>x</I>];
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with the raster origin in the
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<I>lower-left hand corner</I>
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of the tile. That is bottom to top organization. Edge tiles which
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partly fall off the image will be filled out with appropriate zeroed
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areas.
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<P>
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<P>
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Raster pixels are 8-bit packed red, green, blue, alpha samples.
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The macros
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<I>TIFFGetR</I>,
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<I>TIFFGetG</I>,
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<I>TIFFGetB</I>,
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and
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<I>TIFFGetA</I>
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should be used to access individual samples.
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Images without Associated Alpha matting information have a constant
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Alpha of 1.0 (255).
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<P>
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See the
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<I><A HREF="TIFFRGBAImage.3t.html">TIFFRGBAImage</A></I>(3T)
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page for more details on how various image types are converted to RGBA
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values.
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<A NAME="lbAE"> </A>
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<H2>NOTES</H2>
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Samples must be either 1, 2, 4, 8, or 16 bits.
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Colorimetric samples/pixel must be either 1, 3, or 4 (i.e.
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<I>SamplesPerPixel</I>
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minus
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<I>ExtraSamples</I>).
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<P>
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Palette image colormaps that appear to be incorrectly written
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as 8-bit values are automatically scaled to 16-bits.
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<P>
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<I>TIFFReadRGBATile</I>
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is just a wrapper around the more general
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<I><A HREF="TIFFRGBAImage.3t.html">TIFFRGBAImage</A></I>(3T)
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facilities. It's main advantage over the similar
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<I>TIFFReadRGBAImage()</I>
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function is that for large images a single
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buffer capable of holding the whole image doesn't need to be allocated,
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only enough for one tile. The
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<I>TIFFReadRGBAStrip()</I>
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function does a similar operation for stripped images.
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<A NAME="lbAF"> </A>
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<H2>RETURN VALUES</H2>
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1 is returned if the image was successfully read and converted.
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Otherwise, 0 is returned if an error was encountered.
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<A NAME="lbAG"> </A>
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<H2>DIAGNOSTICS</H2>
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All error messages are directed to the
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<I><A HREF="TIFFError.3t.html">TIFFError</A></I>(3T)
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routine.
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<P>
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<B>Sorry, can not handle %d-bit pictures</B>.
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The image had
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<I>BitsPerSample</I>
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other than 1, 2, 4, 8, or 16.
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<P>
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<B>Sorry, can not handle %d-channel images</B>.
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The image had
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<I>SamplesPerPixel</I>
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other than 1, 3, or 4.
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<P>
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<B>Missing needed "PhotometricInterpretation" tag</B>.
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The image did not have a tag that describes how to display
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the data.
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<P>
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<B>No "PhotometricInterpretation" tag, assuming RGB</B>.
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The image was missing a tag that describes how to display it,
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but because it has 3 or 4 samples/pixel, it is assumed to be
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<FONT SIZE="-1">RGB.</FONT>
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<P>
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<B>No "PhotometricInterpretation" tag, assuming min-is-black</B>.
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The image was missing a tag that describes how to display it,
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but because it has 1 sample/pixel, it is assumed to be a grayscale
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or bilevel image.
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<P>
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<B>No space for photometric conversion table</B>.
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There was insufficient memory for a table used to convert
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image samples to 8-bit
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<FONT SIZE="-1">RGB.</FONT>
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<P>
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<B>Missing required "Colormap" tag</B>.
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A Palette image did not have a required
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<I>Colormap</I>
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tag.
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<P>
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<B>No space for tile buffer</B>.
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There was insufficient memory to allocate an i/o buffer.
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<P>
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<B>No space for strip buffer</B>.
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There was insufficient memory to allocate an i/o buffer.
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<P>
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<B>Can not handle format</B>.
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The image has a format (combination of
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<I>BitsPerSample</I>,
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<I>SamplesPerPixel</I>,
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and
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<I>PhotometricInterpretation</I>)
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that
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<I>TIFFReadRGBAImage</I>
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can not handle.
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<P>
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<B>No space for B&W mapping table</B>.
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There was insufficient memory to allocate a table used to map
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grayscale data to
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<FONT SIZE="-1">RGB.</FONT>
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<P>
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<B>No space for Palette mapping table</B>.
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There was insufficient memory to allocate a table used to map
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data to 8-bit
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<FONT SIZE="-1">RGB.</FONT>
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<A NAME="lbAH"> </A>
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<H2>BUGS</H2>
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Orientations other than bottom-left, or top-left are
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not handled correctly.
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<A NAME="lbAI"> </A>
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<H2>SEE ALSO</H2>
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<I><A HREF="libtiff.3t.html">libtiff</A></I>(3T),
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<I><A HREF="TIFFOpen.3t.html">TIFFOpen</A></I>(3T),
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<I><A HREF="TIFFRGBAImage.3t.html">TIFFRGBAImage</A></I>(3T),
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<I><A HREF="TIFFReadRGBAImage.3t.html">TIFFReadRGBAImage</A></I>(3T),
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<I><A HREF="TIFFReadRGBAStrip.3t.html">TIFFReadRGBAStrip</A></I>(3T)
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT><A HREF="#lbAB">NAME</A><DD>
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<DT><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT><A HREF="#lbAE">NOTES</A><DD>
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<DT><A HREF="#lbAF">RETURN VALUES</A><DD>
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<DT><A HREF="#lbAG">DIAGNOSTICS</A><DD>
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<DT><A HREF="#lbAH">BUGS</A><DD>
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<DT><A HREF="#lbAI">SEE ALSO</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="index.html">man2html</A>,
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using the manual pages.<BR>
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Time: 01:31:38 GMT, November 23, 1999
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