grammar

git-svn-id: http://svn.code.sf.net/p/netpbm/code/userguide@2054 9d0c8265-081b-0410-96cb-a4ca84ce46f8

20 files changed, 86 insertions, 103 deletions

diff --git a/libnetpbm_image.html b/libnetpbm_image.html
index e895c738..618b3ae7 100644
--- a/libnetpbm_image.html
+++ b/libnetpbm_image.html
@@ -469,7 +469,7 @@ representation of the color represented by the input tuple, assuming
 that the tuple is an RGB color representation (which is the case if it
 was read from a PPM image).  The output components are based on the
 same scale (maxval) as the input tuple, but are floating point
-nonetheless to avoid losing information due to rounding.  Divide them
+nonetheless to avoid losing information because of rounding.  Divide them
 by the maxval to get normalized [0..1] values.
 
 <p><b>pnm_YCbCr_to_rgbtuple()</b> does the reverse.  <i>pamP</i>
diff --git a/libpbm.html b/libpbm.html
index 169668a0..74a86a97 100644
--- a/libpbm.html
+++ b/libpbm.html
@@ -226,7 +226,7 @@ there may be white space between images.
 <P>If <B>pbm_nextimage() </B> successfully positions to the next
 image, it returns <B>*</B><I>eofP</I> false (0).  If there is no next
 image in the file, it returns <B>*</B><I>eofP</I> true .  If it can't
-position or determine the file status due to a file error, it
+position or determine the file status because of a file error, it
 <a href="liberror.html#error">throws an error</a>.
 
 <P><B>pbm_check()</B> checks for the common file integrity error where
diff --git a/libsystem.html b/libsystem.html
index fa77dfa3..ffed547d 100644
--- a/libsystem.html
+++ b/libsystem.html
@@ -199,9 +199,9 @@ The last argument <em>must</em> be NULL to tell <b>pm_system_lp()</b>
 where the arguments end.
 
 <p>Note that the first argument (&quot;arg0&quot;) to a program is
-conventionally the first word of the command used to run the program,
-as if it were being run due to a shell command.  In other words,
-typically the name of the program.
+conventionally the first word of the command used to run the program, as if it
+were being run for a shell command.  In other words, typically the name of the
+program.
 
 <p>Example:
 
diff --git a/pamarith.html b/pamarith.html
index 9bd5c1a1..1ef36669 100644
--- a/pamarith.html
+++ b/pamarith.html
@@ -172,7 +172,7 @@ left input image is less than the value in the right input image,
 greater than the right.
 
 <p>If the maxvals of the input images are not identical, <b>pamarith</b>
-may claim two values are not equal when in fact they are, due to
+may claim two values are not equal when in fact they are, because of
 the precision with which it does the arithmetic.  However, it will never
 say A is greater than B if A is less than B.
 
diff --git a/pamfixtrunc.html b/pamfixtrunc.html
index 14b8477d..25f681e3 100644
--- a/pamfixtrunc.html
+++ b/pamfixtrunc.html
@@ -45,7 +45,7 @@ the file.  For example, the program ran out of its own input or
 encountered a bug or ran out of space in which to write the output.
 
 <p>Another problem <b>pamfixtrunc</b> deals with is where the file isn't
-actually too small, but due to a system error, a byte in the middle of
+actually too small, but because of a system error, a byte in the middle of
 it cannot be read (think of a disk storage failure).  <b>pamfixtrunc</b>
 reads the input sequentially until it can't read any further, for any
 reason.  So it treats such an image as a truncated one, ignoring all
diff --git a/pamflip.html b/pamflip.html
index c14601fe..e95035bc 100644
--- a/pamflip.html
+++ b/pamflip.html
@@ -170,7 +170,7 @@ is row for column, it will page thrash and run very slowly.  A value
 even slightly too high is the same as infinity.
 
 <p>If you specify <b>-memsize</b> too small, the program will run
-slightly more slowly due to extra overhead in manipulating temporary
+slightly more slowly because of extra overhead in manipulating temporary
 files.  Also, if your environment isn't set up to make temporary files
 possible, <b>pamflip</b> will fail.
 
diff --git a/pamlookup.html b/pamlookup.html
index 51525db7..7eb120aa 100644
--- a/pamlookup.html
+++ b/pamlookup.html
@@ -7,12 +7,10 @@ Updated: 10 November 2002
 <BR>
 <A HREF="#index">Table Of Contents</A>
 
-<A NAME="lbAB">&nbsp;</A>
-<H2>NAME</H2>
+<H2 id="name">NAME</H2>
 pamlookup - map an image to a new image by using it as indices into a table
 
-<A NAME="lbAC">&nbsp;</A>
-<H2>SYNOPSIS</H2>
+<H2 id="synopsis">SYNOPSIS</H2>
 
 <B>pamlookup</B>
 <B>-lookupfile=</B><i>lookupfile</i>
@@ -25,8 +23,7 @@ pamlookup - map an image to a new image by using it as indices into a table
 You may use two hyphens instead of one.  You may separate an option
 name and its value with white space instead of an equals sign.
 
-<A NAME="lbAD">&nbsp;</A>
-<H2>DESCRIPTION</H2>
+<H2 id="description">DESCRIPTION</H2>
 
 <p>This program is part of <a href="index.html">Netpbm</a>.
 
@@ -126,8 +123,7 @@ output reflects the combination of both inputs), use <b>pamstack</b> to combine
 the two into one two-plane image (and use a 2-dimensional lookup table image).
 
 
-<A NAME="options">&nbsp;</A>
-<H2>OPTIONS</H2>
+<H2 id="options">OPTIONS</H2>
 
 <DL COMPACT>
 <DT><B>-lookupfile=</B><i>lookupfile</i>
@@ -167,13 +163,12 @@ shrinking) with the <a href="pamscale.html"><b>pamscale</b></a>
 program.
 
 <p>When you use <b>-fit</b>, <b>pamlookup</b> never fails or warns you
-due to invalid lookup image dimensions, and the <b>-missingcolor</b>
+because of invalid lookup image dimensions, and the <b>-missingcolor</b>
 option has no effect.
 
 </DL>
 
-<A NAME="examples">&nbsp;</a>
-<H2>EXAMPLES</H2>
+<H2 id="examples">EXAMPLES</H2>
 
 <h3>Example: rainfall map</h3>
 
@@ -259,8 +254,7 @@ produce the output:
 </pre>
 
      
-<A NAME="lbAE">&nbsp;</A>
-<H2>SEE ALSO</H2>
+<H2 id="seealso">SEE ALSO</H2>
 
 <A HREF="pnmremap.html">pnmremap</A>,
 <A HREF="ppmmake.html">ppmmake</A>,
@@ -270,22 +264,19 @@ produce the output:
 <A HREF="pam.html">pam</A>
 
 
-<A NAME="history"></A>
-<H2>HISTORY</h2>
+<H2 id="history">HISTORY</h2>
 
 <p><b>pamlookup</b> was new in Netpbm 10.13 (December 2002).
 
 <HR>
-<A NAME="index">&nbsp;</A>
-<H2>Table Of Contents</H2>
+<H2 id="index">Table Of Contents</H2>
 <UL COMPACT>
-<LI><A HREF="#lbAB">NAME</A>
-<LI><A HREF="#lbAC">SYNOPSIS</A>
-<LI><A HREF="#lbAD">DESCRIPTION</A>
+<LI><A HREF="#synopsis">SYNOPSIS</A>
+<LI><A HREF="#description">DESCRIPTION</A>
 <LI><A HREF="#options">OPTIONS</A>
 <LI><A HREF="#examples">EXAMPLES</A>
 <LI><A HREF="#history">HISTORY</A>
-<LI><A HREF="#lbAE">SEE ALSO</A>
+<LI><A HREF="#seealso">SEE ALSO</A>
 </UL>
 </BODY>
 </HTML>
diff --git a/pamtogif.html b/pamtogif.html
index 9c51d2fa..48f8168e 100644
--- a/pamtogif.html
+++ b/pamtogif.html
@@ -321,7 +321,7 @@ royalty-free.  Bryan adapted code from the Independent JPEG Group's
 <b>djpeg</b> for that.
 
 <p>There is no code in <b>pamtogif</b> from Jef's original, but Jef
-may still hold copyright over it due to the way in which it evolved.
+may still hold copyright over it because of the way in which it evolved.
 Virtually all of the code in <b>pamtogif</b> was written by Bryan
 Henderson and contributed to the public domain.
 
diff --git a/pamtotiff.html b/pamtotiff.html
index c7a48a0b..f5f849a1 100644
--- a/pamtotiff.html
+++ b/pamtotiff.html
@@ -70,8 +70,8 @@ ignored all but the first Netpbm image in the input stream.
 <h3 id="output">The Output File</h3>
 
 <P>The output goes to Standard Output.  <b>pamtotiff</b> approaches
-this output file differently from Unix and Netpbm convention.  This is
-entirely due to <b>pamtotiff</b>'s use of the TIFF library to do all
+this output file differently from Unix and Netpbm convention.  This is due
+entirely to <b>pamtotiff</b>'s use of the TIFF library to do all
 TIFF output.
 
 <ul>
@@ -129,7 +129,7 @@ play.
 
 <p>Before Netpbm 8.4 (April 2000), the default was to use LZW compression.
 But then new releases of the TIFF library started omitting the LZW
-compression capability due to concern about patents on LZW.  So
+compression capability because of concern about patents on LZW.  So
 since then, the default has been no compression.  The LZW patents have
 now expired and new TIFF libraries do LZW, but the <b>pamtotiff</b>
 behavior remains the same for compatibility with older TIFF libraries
@@ -241,7 +241,7 @@ results in better compression and is generally preferred for bilevel
 coding.
 
 <P>Before February 2001, <B>pamtotiff</B> always produced
-&quot;minimum is black,&quot; due to a bug.  In either case,
+&quot;minimum is black,&quot; because of a bug.  In either case,
 <B>pamtotiff</B> sets the photometric interpretation tag in the TIFF
 output according to which photometric is actually used.
 
diff --git a/pbmpage.html b/pbmpage.html
index 542efc7a..c9f2d6b3 100644
--- a/pbmpage.html
+++ b/pbmpage.html
@@ -6,20 +6,17 @@ Updated: 01 May 2000
 <BR>
 <A HREF="#index">Table Of Contents</A>
 
-<A NAME="lbAB">&nbsp;</A>
-<H2>NAME</H2>
+<H2 id="name">NAME</H2>
 
 pbmpage - create a one page test pattern for printing
 
-<A NAME="lbAC">&nbsp;</A>
-<H2>SYNOPSIS</H2>
+<H2 id="synopsis">SYNOPSIS</H2>
 
 <B>pbmpage</B>
 [<B>-a4</B>]
 <I>test_pattern</I>
 
-<A NAME="lbAD">&nbsp;</A>
-<H2>DESCRIPTION</H2>
+<H2 id="description">DESCRIPTION</H2>
 
 <p>This program is part of <a href="index.html">Netpbm</a>.
 
@@ -40,7 +37,7 @@ only the printer, but any converter or driver software along the
 printing path.  Any one of these components may adjust margins, crop
 the image, erase edges, and such.
 
-<P>If, due to addition of margins, the printer refuses to print the
+<P>If, because of addition of margins, the printer refuses to print the
 image because it is too big, use <B>pamcut</B> to cut the right and
 bottom edges off the test pattern until it is small enough to print.
 
@@ -69,8 +66,7 @@ page, the other starting from the lower left corner of the page.  Both
 extend 1/2&quot; toward the center of the page at 45 degrees.
 </DL>
 
-<A NAME="lbAE">&nbsp;</A>
-<H2>OPTIONS</H2>
+<H2 id="options">OPTIONS</H2>
 
 <DL COMPACT>
 <DT><B>-a4</B>
@@ -81,15 +77,13 @@ wide x 11&quot; high).
 
 </DL>
 
-<A NAME="lbAF">&nbsp;</A>
-<H2>SEE ALSO</H2>
+<H2 id="seealso">SEE ALSO</H2>
 
 <B><A HREF="pbmtoppa.html">pbmtoppa</A></B>,
 <B><A HREF="pamcut.html">pamcut</A></B>,
 <B><A HREF="pbm.html">pbm</A></B>
 
-<A NAME="lbAG">&nbsp;</A>
-<H2>AUTHOR</H2>
+<H2 id="author">AUTHOR</H2>
 
 Tim Norman.  Copyright (C) 1998.  Licensed under GNU Public License
 
@@ -97,15 +91,13 @@ Tim Norman.  Copyright (C) 1998.  Licensed under GNU Public License
 domain by its author.
 
 <HR>
-<A NAME="index">&nbsp;</A>
-<H2>Table Of Contents</H2>
+<H2 id="index">Table Of Contents</H2>
 <UL>
-<LI><A HREF="#lbAB">NAME</A>
-<LI><A HREF="#lbAC">SYNOPSIS</A>
-<LI><A HREF="#lbAD">DESCRIPTION</A>
-<LI><A HREF="#lbAE">OPTIONS</A>
-<LI><A HREF="#lbAF">SEE ALSO</A>
-<LI><A HREF="#lbAG">AUTHOR</A>
+<LI><A HREF="#synopsis">SYNOPSIS</A>
+<LI><A HREF="#description">DESCRIPTION</A>
+<LI><A HREF="#options">OPTIONS</A>
+<LI><A HREF="#seealso">SEE ALSO</A>
+<LI><A HREF="#author">AUTHOR</A>
 </UL>
 </BODY>
 </HTML>
diff --git a/pnmcut.html b/pnmcut.html
index 0d7d2931..25884aff 100644
--- a/pnmcut.html
+++ b/pnmcut.html
@@ -4,14 +4,13 @@
 <H1>pnmcut</H1>
 Updated: 02 February 2009
 <BR>
-<A HREF="#index">Table Of Contents</A>
 
 <H2>NAME</H2>
 
 <B>pnmcut</B> - replaced by pamcut
 
 
-<H2>DESCRIPTION</H2>
+<H2 >DESCRIPTION</H2>
 
 <p>This program is part of <a href="index.html">Netpbm</a>.
 
@@ -22,7 +21,7 @@ adds many additional functions, including the ability to process PAM
 images.
 
 <p><b>pnmcut</b> remained in the Netpbm package until Netpbm 10.46 (March
-2009) because of hopes that it had fewer bugs than <b>pamcut</b> due to its
+2009) because of hopes that it had fewer bugs than <b>pamcut</b> because of its
 age.  But now it would just be clutter.
 
 <p>In Netpbm before 9.20, use the manual for <b>pamcut</b> with
diff --git a/pnmdepth.html b/pnmdepth.html
index 0ca740e5..1ac8d13c 100644
--- a/pnmdepth.html
+++ b/pnmdepth.html
@@ -21,7 +21,7 @@ use the <b>pamdepth</b> manual for <b>pnmdepth</b> as long as you ignore
 features that were added after Netpbm 10.31.
 
 <p>For backward compatibility, the name 'pnmdepth' continues to exist
-as an alias for 'pamdepth'.  But due to a bug, that name doesn't work
+as an alias for 'pamdepth'.  But because of a bug, that name doesn't work
 in Netpbm 10.32.  You have to fix the symbolic link.
 
 </BODY>
diff --git a/pnmhisteq.html b/pnmhisteq.html
index f5323a8e..d73857c6 100644
--- a/pnmhisteq.html
+++ b/pnmhisteq.html
@@ -91,9 +91,9 @@ composite.
 <p>Use <b>pnmhistmap</b> to see the result.  Run a color image through
 <b>ppmtopgm</b> first so that you see a histogram of the luminosity instead of
 histograms of the three color components.  It should generally show a flat
-histogram.  But due to the quantization effects described above, you might see
-high bars interleaved with low bars, with the local average being flat.  To
-see local averages, use the <b>-width</b> option of <b>pnmhistmap</b>.
+histogram.  But because of the quantization effects described above, you might
+see high bars interleaved with low bars, with the local average being flat.
+To see local averages, use the <b>-width</b> option of <b>pnmhistmap</b>.
 
 
 <H2 id="options">OPTIONS</H2>
diff --git a/pnmnorm.html b/pnmnorm.html
index 5d3ca492..f186d42f 100644
--- a/pnmnorm.html
+++ b/pnmnorm.html
@@ -162,7 +162,7 @@ stretch to zero intensity as described above, and then raises the
 former and lowers the latter as needed to limit the expansion to the
 amount you specified.
 
-<p>When <b>pnmnorm</b> limits the expansion due to <b>-maxexpand</b>,
+<p>When <b>pnmnorm</b> limits the expansion because of <b>-maxexpand</b>,
 it tells you about it with a message like this:
 <pre>
 <tt>
diff --git a/pnmscale.html b/pnmscale.html
index bfcfee78..f14903cc 100644
--- a/pnmscale.html
+++ b/pnmscale.html
@@ -22,8 +22,8 @@ plus adds many additional functions, including the ability to process PAM
 images.
 
 <p><b>pnmscale</b> remained in the Netpbm package until Netpbm 10.46 (March
-2009) because of hopes that it had fewer bugs than <b>pamscale</b> due to its
-age.  But now it would just be clutter.
+2009) because of hopes that it had fewer bugs than <b>pamscale</b> because of
+its age.  But now it would just be clutter.
 
 <p>In Netpbm before 10.20, use the manual for <b>pamscale</b> with
 <b>pnmscale</b>.  Features that are in <b>pamscale</b> but not <b>pnmscale</b>
diff --git a/ppm3d.html b/ppm3d.html
index 08a5623c..8aa9edcc 100644
--- a/ppm3d.html
+++ b/ppm3d.html
@@ -41,11 +41,10 @@ which is monochrome.  Viewed through red-green glasses it is yellow,
 but without any other color in the field, your brain tends to see it
 as grayscale.
 
-<p>In the color version, <b>ppm3d</b> generates a result which is
-close to the color of the original.  It's not great, though,
-due to the fact that each eye necessarily cannot see the entire
-spectrum.  Red and cyan don't work well, but most other colors --
-especially when heavily saturated -- come out quite well.
+<p>In the color version, <b>ppm3d</b> generates a result which is close to the
+color of the original.  It's not great, though, because each eye necessarily
+cannot see the entire spectrum.  Red and cyan don't work well, but most other
+colors -- especially when heavily saturated -- come out quite well.
 
 <p>To view a color anaglyph stereogram, you need glasses with a left
 lens that admits only red light and a right lens that admits only blue
diff --git a/ppmglobe.html b/ppmglobe.html
index a6474b3f..ab87b8ac 100644
--- a/ppmglobe.html
+++ b/ppmglobe.html
@@ -104,7 +104,7 @@ the background is always black.
 <DT><B>-closeok</B>
 <DD>
 This means it is OK if the background isn't exactly the color you specify.
-Sometimes, it is impossible to represent a named color exactly due to the
+Sometimes, it is impossible to represent a named color exactly because of the
 precision (i.e. maxval) of the image's color space.  If you specify
 <b>-closeok</b> and <b>ppmglobe</b> can't represent the color you name
 exactly, it will use instead the closest color to it that is possible.
diff --git a/ppmshadow.html b/ppmshadow.html
index 2089c7a7..d3ac3532 100644
--- a/ppmshadow.html
+++ b/ppmshadow.html
@@ -5,12 +5,10 @@
 Updated: 17 April 2005
 <BR><A HREF="#index">Table Of Contents</A>
 
-<A NAME="lbAB">&nbsp;</A>
-<H2>NAME</H2>
+<H2 id="name">NAME</H2>
 ppmshadow - add simulated shadows to a PPM image
 
-<A NAME="lbAC">&nbsp;</A>
-<H2>SYNOPSIS</H2>
+<H2 id="synopsis">SYNOPSIS</H2>
 
 <B>ppmshadow</B>
 [<B>-b</B> <I>blur_size</I>]
@@ -21,8 +19,7 @@ ppmshadow - add simulated shadows to a PPM image
 [<I>ppmfile</I>]
 
 
-<A NAME="lbAD">&nbsp;</A>
-<H2>DESCRIPTION</H2>
+<H2 id="description">DESCRIPTION</H2>
 
 <p>This program is part of <a href="index.html">Netpbm</a>.
 
@@ -48,8 +45,7 @@ image.  The output image is the same dimensions as the input image.
 before running <b>ppmshadow</b> on it.  You can use <b>ppmmake</b> to make
 the background image (just an image of a solid color).
 
-<A NAME="lbAE">&nbsp;</A>
-<H2>OPTIONS</H2>
+<H2 id="options">OPTIONS</H2>
 
 <DL COMPACT>
 <DT><B>-b</B> <I>blur_size</I>
@@ -101,8 +97,7 @@ same as the horizontal offset (above), upward.
 </DL>
 
 
-<A NAME="files"></a>
-<H2>FILES</H2>
+<H2 id="files">FILES</H2>
 
 <p>Input is a PPM file named by the <I>ppmfile</I> command line
 argument; if you don't specify <I>ppmfile</I>, the input is Standard
@@ -174,8 +169,7 @@ Everything but the foreground (foreground area is black).
 
 </DL>
 
-<A NAME="lbAG">&nbsp;</A>
-<H2>LIMITATIONS</H2>
+<H2 id="limitations">LIMITATIONS</H2>
 
 <p>The source image must contain sufficient space on the edges in the
 direction in which the shadow is cast to contain the shadow -- if it
@@ -239,8 +233,7 @@ first and then add the shadow, you'll get an unsightly jagged stripe
 between the edge of material and its shadow, due to resampled pixels
 intermediate between the image and background obscuring the shadow.
 
-<A NAME="lbAH">&nbsp;</A>
-<H2>EXIT STATUS</H2>
+<H2 id="exitstatus">EXIT STATUS</H2>
 
 <B>ppmshadow</B> returns status 0 if processing was completed without
 errors, and a nonzero Unix error code if an error prevented generation
@@ -250,8 +243,7 @@ without returning a nonzero error code.  When this happens, the output
 file will be empty, so be sure to test this if you need to know if the
 program succeeded. 
 
-<A NAME="seealso">&nbsp;</A>
-<H2>SEE ALSO</H2>
+<H2 id="seealso">SEE ALSO</H2>
 
 <B><A HREF="pnm.html">pnm</A></B>,
 <B><A HREF="pnmmargin.html">pnmmargin</A></B>,
@@ -261,15 +253,13 @@ program succeeded.
 <B><A HREF="ppm.html">ppm</A></B>
 
 
-<A NAME="lbAJ">&nbsp;</A>
-<H2>AUTHOR</H2>
+<H2 id="author">AUTHOR</H2>
 
 John Walker &lt;<A
 HREF="http://www.fourmilab.ch">http://www.fourmilab.ch</A>&gt; August
 8, 1997
 
-<A NAME="lbAK">&nbsp;</A>
-<H2>COPYRIGHT</H2>
+<H2 id="copyright">COPYRIGHT</H2>
 This software is in the public domain.  Permission to use, copy,
 modify, and distribute this software and its documentation for any
 purpose and without fee is hereby granted, without any conditions or
@@ -277,19 +267,17 @@ restrictions.
 
 
 <HR>
-<A NAME="index">&nbsp;</A>
-<H2>Table Of Contents</H2>
+<H2 id="index">Table Of Contents</H2>
 <UL>
-<LI><A HREF="#lbAB">NAME</A>
-<LI><A HREF="#lbAC">SYNOPSIS</A>
-<LI><A HREF="#lbAD">DESCRIPTION</A>
-<LI><A HREF="#lbAE">OPTIONS</A>
+<LI><A HREF="#synopsis">SYNOPSIS</A>
+<LI><A HREF="#description">DESCRIPTION</A>
+<LI><A HREF="#options">OPTIONS</A>
 <LI><A HREF="#files">FILES</A>
-<LI><A HREF="#lbAG">LIMITATIONS</A>
-<LI><A HREF="#lbAH">EXIT STATUS</A>
+<LI><A HREF="#limitations">LIMITATIONS</A>
+<LI><A HREF="#exitstatus">EXIT STATUS</A>
 <LI><A HREF="#seealso">SEE ALSO</A>
-<LI><A HREF="#lbAJ">AUTHOR</A>
-<LI><A HREF="#lbAK">COPYRIGHT</A>
+<LI><A HREF="#author">AUTHOR</A>
+<LI><A HREF="#copyright">COPYRIGHT</A>
 </UL>
 </BODY>
 </HTML>
diff --git a/ppmtoxpm.html b/ppmtoxpm.html
index 5c2af35f..1530682b 100644
--- a/ppmtoxpm.html
+++ b/ppmtoxpm.html
@@ -63,7 +63,7 @@ of the color code affects the size of the image stream.
 <b>ppmtoxpm</b> tries to make it as short as possible.  That length
 is, of course, determined by the number of colors in the image.
 <b>ppmtoxpm</b> counts the colors in the image, excluding those that
-will be transparent in the output due to your alpha mask, and chooses
+will be transparent in the output because of your alpha mask, and chooses
 a color code length accordingly.  There are 92 printable characters
 that can be used in a color code.  Therefore, if you have 92 or fewer
 colors, your color codes will be one character.  If you have more than
diff --git a/pstopnm.html b/pstopnm.html
index 9aef79f9..71b573e8 100644
--- a/pstopnm.html
+++ b/pstopnm.html
@@ -175,7 +175,7 @@ image to form the bordered subject image is controlled by the options
 a BoundingBox statement in the input, and you don't specify image area
 coordinates on the command line, <B>pstopnm</B> uses default values.
 If your input is from Standard Input, <B>pstopnm</B> does not use the
-BoundingBox values (due to the technical difficulty of extracting that
+BoundingBox values (because of the technical difficulty of extracting that
 information and still feeding the file to Ghostscript), so you either
 have to specify the image area coordinates or take the default.
 
@@ -240,6 +240,17 @@ large enough to accommodate the subject image (no borders).  Remember
 (above) that <b>pstopnm</b> trims the edges of the bordered subject
 image to fit the computed output size.
 
+
+<h3 id="ghostscriptlimitations">Ghostscript Limitations</h3>
+
+<p>Tests done in 2013 with Ghostscript 8.71 indicate that Ghostscript's
+<b>pgmraw</b> output driver has some kind of rounding error that causes the
+pixel values to change slightly, and that means <b>pstopnm</b> generates
+incorrect output when you have monochrome Postscript input.  But with color
+Postscript input, <b>pstopnm</b> uses Ghostscript's <b>ppmraw</b> output
+driver and generates correct PPM output.
+
+
 <h3 id="usagenotes">Usage Notes</h3>
 
 <p>There is some good advice on converting to and from Postscript, in the
@@ -281,6 +292,9 @@ wouldn't use those in a program).
 </kbd>
 </pre>
 
+<p>Note that Ghostscript bugs can keep this from doing a perfect
+reversible conversion.
+
 
 <H2 id="options">OPTIONS</H2>