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RE: [XSL-FO] Re: forcing line breaks

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  • David Cramer
    David, Could you give an example of this technique? What s a zero-width space and how do you intersperse them between letters in a given text node with xsl?
    Message 1 of 19 , Dec 5, 2001
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      David,
      Could you give an example of this technique? What's a zero-width space
      and how do you intersperse them between letters in a given text node
      with xsl?

      Thanks,
      David

      -----Original Message-----
      From: dvd@... [mailto:dvd@...]
      Sent: Wednesday, December 05, 2001 4:47 PM
      To: xsl-fo@yahoogroups.com
      Subject: Re: [XSL-FO] Re: forcing line breaks

      <snip>

      Attributes are of no use here. In XEP, you may add zero-width spaces
      wherever you want thus allowing line breaks. Just intersperse letters
      with zero-width spaces in all words inside table sells and the text
      will break right at the cells' edges.

      Sincerely,
      David Tolpin
      RenderX
    • dvd@renderx.com
      ... Zero-width space IS a native FO solution. Zero-width space is a Unicode character. An FO formatter is expected to be able to break lines on zero-width
      Message 2 of 19 , Dec 5, 2001
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        >
        >
        > Thank you for the good tip, David. It's too late in our dev cycle to
        > consider using a different renderer, and I'm getting the impression
        > that there's no native FO solution.
        >
        > Anybody have other ideas? Or am I just up the creek w/o a paddle?

        Zero-width space IS a native FO solution. Zero-width space is a Unicode
        character. An FO formatter is expected to be able to break lines on
        zero-width spaces.

        It is a deficiency of a formatter not to handle zero-width spaces
        properly.

        David Tolpin
        RenderX
      • barrett808
        Well, that just shows you how little I know about XSL...Is there some convenient way to transform a text element to one with zero-width spaces interspersed?
        Message 3 of 19 , Dec 5, 2001
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          Well, that just shows you how little I know about XSL...Is there some
          convenient way to transform a text element to one with zero-width
          spaces interspersed? Seems that would be a nifty transformation to
          have in our toolkit.


          --- In XSL-FO@y..., dvd@r... wrote:
          > >
          > >
          > > Thank you for the good tip, David. It's too late in our dev cycle
          to
          > > consider using a different renderer, and I'm getting the
          impression
          > > that there's no native FO solution.
          > >
          > > Anybody have other ideas? Or am I just up the creek w/o a paddle?
          >
          > Zero-width space IS a native FO solution. Zero-width space is a
          Unicode
          > character. An FO formatter is expected to be able to break lines on
          > zero-width spaces.
          >
          > It is a deficiency of a formatter not to handle zero-width spaces
          > properly.
          >
          > David Tolpin
          > RenderX
        • Nikolai Grigoriev
          Hi, ...
          Message 4 of 19 , Dec 6, 2001
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            Hi,

            > Well, that just shows you how little I know about XSL...Is there some
            > convenient way to transform a text element to one with zero-width
            > spaces interspersed? Seems that would be a nifty transformation to
            > have in our toolkit.

            <xsl:template match="text()" mode="insert-zero-spaces">
            <xsl:call-template name="intersperse-with-zero-spaces">
            <xsl:with-param name="str" select="."/>
            </xsl:call-template>
            </xsl:template>

            <xsl:template name="intersperse-with-zero-spaces">
            <xsl:param name="str"/>
            <xsl:variable name="spacechars">

                  
                 ​
            </xsl:variable>

            <xsl:if test="string-length($str) > 1">
            <xsl:variable name="c1" select="substring($str, 1, 1)/>
            <xsl:variable name="c2" select="substring($str, 2, 1)/>

            <xsl:value-of select="$c1"/>
            <!-- Insert a zero-width space between any two non-space characters -->
            <xsl:if test="not(contains($spacechars, $c1) or contains($spacechars,
            $c2))">
            <xsl:text>​</xsl:text>
            </xsl:if>

            <xsl:call-template name="intersperse-with-zero-spaces">
            <xsl:with-param name="str" select="substring($str, 2)"/>
            </xsl:call-template>
            </xsl:if>
            </xsl:call-template>

            Regards,

            Nikolai Grigoriev
            RenderX
          • barrett808
            Thank you, Nikolai. This looks promising, but I m having problems making it work. Here s the code (slightly adapted) I m using, and it basically just spits out
            Message 5 of 19 , Dec 6, 2001
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              Thank you, Nikolai. This looks promising, but I'm having problems
              making it work. Here's the code (slightly adapted) I'm using, and it
              basically just spits out the text content of the elements with a
              bunch of white space between them.

              <?xml version="1.0" encoding="UTF-16"?>
              <xsl:stylesheet version="1.0"
              xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
              xmlns:fo="http://www.w3.org/1999/XSL/Format">
              <!-- This template sprinkles zero-width space characters in a
              text element -->
              <xsl:template match="text()" mode="insert-zero-spaces">
              <xsl:call-template name="intersperse-with-zero-
              spaces">
              <xsl:with-param name="str" select="."/>
              </xsl:call-template>
              </xsl:template>
              <xsl:template name="intersperse-with-zero-spaces">
              <xsl:param name="str"/>
              <xsl:variable name="spacechars">

                    
                   ​
              </xsl:variable>
              <xsl:if test="string-length($str) > 1">
              <xsl:variable name="c1" select="substring
              ($str, 1, 1)"/>
              <xsl:variable name="c2" select="substring
              ($str, 2, 1)"/>
              <xsl:value-of select="$c1"/>
              <!-- Insert a zero-width space between any
              two non-space characters -->
              <!-- <xsl:if test="not(contains($spacechars,
              $c1) or contains($spacechars,
              $c2))"> -->
              <!-- <xsl:text>​</xsl:text> -->
              <xsl:text>F</xsl:text>
              <!-- </xsl:if> -->
              <xsl:call-template name="intersperse-with-
              zero-spaces">
              <xsl:with-param name="str"
              select="substring($str, 2)"/>
              </xsl:call-template>
              </xsl:if>
              </xsl:template>
              </xsl:stylesheet>


              --- In XSL-FO@y..., "Nikolai Grigoriev" <grig@r...> wrote:
              > Hi,
              >
              > > Well, that just shows you how little I know about XSL...Is there
              some
              > > convenient way to transform a text element to one with zero-width
              > > spaces interspersed? Seems that would be a nifty transformation to
              > > have in our toolkit.
              >
              > <xsl:template match="text()" mode="insert-zero-spaces">
              > <xsl:call-template name="intersperse-with-zero-spaces">
              > <xsl:with-param name="str" select="."/>
              > </xsl:call-template>
              > </xsl:template>
              >
              > <xsl:template name="intersperse-with-zero-spaces">
              > <xsl:param name="str"/>
              > <xsl:variable name="spacechars">
              >
              >       
              >      ​
              > </xsl:variable>
              >
              > <xsl:if test="string-length($str) > 1">
              > <xsl:variable name="c1" select="substring($str, 1, 1)/>
              > <xsl:variable name="c2" select="substring($str, 2, 1)/>
              >
              > <xsl:value-of select="$c1"/>
              > <!-- Insert a zero-width space between any two non-space
              characters -->
              > <xsl:if test="not(contains($spacechars, $c1) or contains
              ($spacechars,
              > $c2))">
              > <xsl:text>​</xsl:text>
              > </xsl:if>
              >
              > <xsl:call-template name="intersperse-with-zero-spaces">
              > <xsl:with-param name="str" select="substring($str, 2)"/>
              > </xsl:call-template>
              > </xsl:if>
              > </xsl:call-template>
              >
              > Regards,
              >
              > Nikolai Grigoriev
              > RenderX
            • barrett808
              er, here s the actual code (minus spuriously commented out lines):
              Message 6 of 19 , Dec 6, 2001
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                er, here's the actual code (minus spuriously commented out lines):

                <?xml version="1.0" encoding="UTF-16"?>
                <xsl:stylesheet version="1.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:fo="http://www.w3.org/1999/XSL/Format">
                <!-- This template sprinkles zero-width space characters in a
                text element -->
                <xsl:template match="text()" mode="insert-zero-spaces">
                <xsl:call-template name="intersperse-with-zero-
                spaces">
                <xsl:with-param name="str" select="."/>
                </xsl:call-template>
                </xsl:template>
                <xsl:template name="intersperse-with-zero-spaces">
                <xsl:param name="str"/>
                <xsl:variable name="spacechars">

                      
                     ​
                </xsl:variable>
                <xsl:if test="string-length($str) > 1">
                <xsl:variable name="c1" select="substring
                ($str, 1, 1)"/>
                <xsl:variable name="c2" select="substring
                ($str, 2, 1)"/>
                <xsl:value-of select="$c1"/>
                <!-- Insert a zero-width space between any
                two non-space characters -->
                <xsl:if test="not(contains($spacechars, $c1)
                or contains($spacechars,
                $c2))">
                <xsl:text>​</xsl:text>
                <xsl:text>F</xsl:text>
                </xsl:if>
                <xsl:call-template name="intersperse-with-
                zero-spaces">
                <xsl:with-param name="str"
                select="substring($str, 2)"/>
                </xsl:call-template>
                </xsl:if>
                </xsl:template>
                </xsl:stylesheet>
              • barrett808
                Ah, progress: taking out the mode= insert-zero-spaces attribute from the first template gets me strings with embedded nonprintable characters, which is a lot
                Message 7 of 19 , Dec 6, 2001
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                  Ah, progress: taking out the mode="insert-zero-spaces" attribute from
                  the first template gets me strings with embedded nonprintable
                  characters, which is a lot closer. More to follow...

                  --- In XSL-FO@y..., "barrett808" <blackbox@b...> wrote:
                  > Thank you, Nikolai. This looks promising, but I'm having problems
                  > making it work. Here's the code (slightly adapted) I'm using, and
                  it
                  > basically just spits out the text content of the elements with a
                  > bunch of white space between them.
                  >
                  > <?xml version="1.0" encoding="UTF-16"?>
                  > <xsl:stylesheet version="1.0"
                  > xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                  > xmlns:fo="http://www.w3.org/1999/XSL/Format">
                  > <!-- This template sprinkles zero-width space characters in a
                  > text element -->
                  > <xsl:template match="text()" mode="insert-zero-spaces">
                  > <xsl:call-template name="intersperse-with-zero-
                  > spaces">
                  > <xsl:with-param name="str" select="."/>
                  > </xsl:call-template>
                  > </xsl:template>
                  > <xsl:template name="intersperse-with-zero-spaces">
                  > <xsl:param name="str"/>
                  > <xsl:variable name="spacechars">
                  >
                  >       
                  >      ​
                  > </xsl:variable>
                  > <xsl:if test="string-length($str) > 1">
                  > <xsl:variable name="c1" select="substring
                  > ($str, 1, 1)"/>
                  > <xsl:variable name="c2" select="substring
                  > ($str, 2, 1)"/>
                  > <xsl:value-of select="$c1"/>
                  > <!-- Insert a zero-width space between any
                  > two non-space characters -->
                  > <!-- <xsl:if test="not(contains($spacechars,
                  > $c1) or contains($spacechars,
                  > $c2))"> -->
                  > <!-- <xsl:text>​</xsl:text> -->
                  > <xsl:text>F</xsl:text>
                  > <!-- </xsl:if> -->
                  > <xsl:call-template name="intersperse-with-
                  > zero-spaces">
                  > <xsl:with-param name="str"
                  > select="substring($str, 2)"/>
                  > </xsl:call-template>
                  > </xsl:if>
                  > </xsl:template>
                  > </xsl:stylesheet>
                  >
                  >
                  > --- In XSL-FO@y..., "Nikolai Grigoriev" <grig@r...> wrote:
                  > > Hi,
                  > >
                  > > > Well, that just shows you how little I know about XSL...Is
                  there
                  > some
                  > > > convenient way to transform a text element to one with zero-
                  width
                  > > > spaces interspersed? Seems that would be a nifty transformation
                  to
                  > > > have in our toolkit.
                  > >
                  > > <xsl:template match="text()" mode="insert-zero-spaces">
                  > > <xsl:call-template name="intersperse-with-zero-spaces">
                  > > <xsl:with-param name="str" select="."/>
                  > > </xsl:call-template>
                  > > </xsl:template>
                  > >
                  > > <xsl:template name="intersperse-with-zero-spaces">
                  > > <xsl:param name="str"/>
                  > > <xsl:variable name="spacechars">
                  > >
                  > >       
                  > >      ​
                  > > </xsl:variable>
                  > >
                  > > <xsl:if test="string-length($str) > 1">
                  > > <xsl:variable name="c1" select="substring($str, 1, 1)/>
                  > > <xsl:variable name="c2" select="substring($str, 2, 1)/>
                  > >
                  > > <xsl:value-of select="$c1"/>
                  > > <!-- Insert a zero-width space between any two non-space
                  > characters -->
                  > > <xsl:if test="not(contains($spacechars, $c1) or contains
                  > ($spacechars,
                  > > $c2))">
                  > > <xsl:text>​</xsl:text>
                  > > </xsl:if>
                  > >
                  > > <xsl:call-template name="intersperse-with-zero-spaces">
                  > > <xsl:with-param name="str" select="substring($str,
                  2)"/>
                  > > </xsl:call-template>
                  > > </xsl:if>
                  > > </xsl:call-template>
                  > >
                  > > Regards,
                  > >
                  > > Nikolai Grigoriev
                  > > RenderX
                • barrett808
                  Okay, finally got it work exactly as I want it to, thanks Nikolai! Unfortunately, my FO renderer (XSL Formatter by Antenna House) doesn t seem to like these
                  Message 8 of 19 , Dec 6, 2001
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                    Okay, finally got it work exactly as I want it to, thanks Nikolai!
                    Unfortunately, my FO renderer (XSL Formatter by Antenna House)
                    doesn't seem to like these zero-width spaces. My name strings come
                    out as "L? a? s? t? N? a? m? e"

                    D'oh.


                    --- In XSL-FO@y..., "barrett808" <blackbox@b...> wrote:
                    > Ah, progress: taking out the mode="insert-zero-spaces" attribute
                    from
                    > the first template gets me strings with embedded nonprintable
                    > characters, which is a lot closer. More to follow...
                    >
                    > --- In XSL-FO@y..., "barrett808" <blackbox@b...> wrote:
                    > > Thank you, Nikolai. This looks promising, but I'm having problems
                    > > making it work. Here's the code (slightly adapted) I'm using, and
                    > it
                    > > basically just spits out the text content of the elements with a
                    > > bunch of white space between them.
                    > >
                    > > <?xml version="1.0" encoding="UTF-16"?>
                    > > <xsl:stylesheet version="1.0"
                    > > xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                    > > xmlns:fo="http://www.w3.org/1999/XSL/Format">
                    > > <!-- This template sprinkles zero-width space characters in a
                    > > text element -->
                    > > <xsl:template match="text()" mode="insert-zero-spaces">
                    > > <xsl:call-template name="intersperse-with-zero-
                    > > spaces">
                    > > <xsl:with-param name="str" select="."/>
                    > > </xsl:call-template>
                    > > </xsl:template>
                    > > <xsl:template name="intersperse-with-zero-spaces">
                    > > <xsl:param name="str"/>
                    > > <xsl:variable name="spacechars">
                    > >
                    > >       
                    > >      ​
                    > > </xsl:variable>
                    > > <xsl:if test="string-length($str) > 1">
                    > > <xsl:variable name="c1" select="substring
                    > > ($str, 1, 1)"/>
                    > > <xsl:variable name="c2" select="substring
                    > > ($str, 2, 1)"/>
                    > > <xsl:value-of select="$c1"/>
                    > > <!-- Insert a zero-width space between any
                    > > two non-space characters -->
                    > > <!-- <xsl:if test="not(contains($spacechars,
                    > > $c1) or contains($spacechars,
                    > > $c2))"> -->
                    > > <!-- <xsl:text>​</xsl:text> -->
                    > > <xsl:text>F</xsl:text>
                    > > <!-- </xsl:if> -->
                    > > <xsl:call-template name="intersperse-with-
                    > > zero-spaces">
                    > > <xsl:with-param name="str"
                    > > select="substring($str, 2)"/>
                    > > </xsl:call-template>
                    > > </xsl:if>
                    > > </xsl:template>
                    > > </xsl:stylesheet>
                    > >
                    > >
                    > > --- In XSL-FO@y..., "Nikolai Grigoriev" <grig@r...> wrote:
                    > > > Hi,
                    > > >
                    > > > > Well, that just shows you how little I know about XSL...Is
                    > there
                    > > some
                    > > > > convenient way to transform a text element to one with zero-
                    > width
                    > > > > spaces interspersed? Seems that would be a nifty
                    transformation
                    > to
                    > > > > have in our toolkit.
                    > > >
                    > > > <xsl:template match="text()" mode="insert-zero-spaces">
                    > > > <xsl:call-template name="intersperse-with-zero-spaces">
                    > > > <xsl:with-param name="str" select="."/>
                    > > > </xsl:call-template>
                    > > > </xsl:template>
                    > > >
                    > > > <xsl:template name="intersperse-with-zero-spaces">
                    > > > <xsl:param name="str"/>
                    > > > <xsl:variable name="spacechars">
                    > > >
                    > > >       
                    > > >      ​
                    > > > </xsl:variable>
                    > > >
                    > > > <xsl:if test="string-length($str) > 1">
                    > > > <xsl:variable name="c1" select="substring($str, 1, 1)/>
                    > > > <xsl:variable name="c2" select="substring($str, 2, 1)/>
                    > > >
                    > > > <xsl:value-of select="$c1"/>
                    > > > <!-- Insert a zero-width space between any two non-
                    space
                    > > characters -->
                    > > > <xsl:if test="not(contains($spacechars, $c1) or
                    contains
                    > > ($spacechars,
                    > > > $c2))">
                    > > > <xsl:text>​</xsl:text>
                    > > > </xsl:if>
                    > > >
                    > > > <xsl:call-template name="intersperse-with-zero-spaces">
                    > > > <xsl:with-param name="str" select="substring($str,
                    > 2)"/>
                    > > > </xsl:call-template>
                    > > > </xsl:if>
                    > > > </xsl:call-template>
                    > > >
                    > > > Regards,
                    > > >
                    > > > Nikolai Grigoriev
                    > > > RenderX
                  • Nikolai Grigoriev
                    ... Hmm. For me, it worked in Saxon, XT, and Xalan after correcting several evident misprints. Below is the full text of my testing stylesheet. My guess: you
                    Message 9 of 19 , Dec 6, 2001
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                      > Thank you, Nikolai. This looks promising, but I'm having problems
                      > making it work. Here's the code (slightly adapted) I'm using, and it
                      > basically just spits out the text content of the elements with a
                      > bunch of white space between them.

                      Hmm. For me, it worked in Saxon, XT, and Xalan after correcting several
                      evident misprints. Below is the full text of my testing stylesheet.

                      My guess: you have result indenting turned on. You need to insert

                      <xsl:output method="xml" indent="no"/>

                      at the top of your stylesheet, to limit XSLT processor's freedom
                      to rearrange white space.

                      Regards,
                      Nikolai

                      P.S. Here's what I used for test. It's identity transformation,
                      plus the template that I posted originally.

                      <xsl:stylesheet version="1.0"
                      xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
                      <xsl:output method="xml" indent="no"/>

                      <!-- Everything but test nodes: identity transformation -->
                      <xsl:template match="/|*|@*|comment()|processing-instruction()">
                      <xsl:copy>
                      <xsl:apply-templates
                      select="*|@*|text()|comment()|processing-instruction()"/>
                      </xsl:copy>
                      </xsl:template>


                      <!-- Text nodes: intercalate with zwsp's -->
                      <xsl:template match="text()">
                      <xsl:call-template name="intersperse-with-zero-spaces">
                      <xsl:with-param name="str" select="."/>
                      </xsl:call-template>
                      </xsl:template>

                      <!-- Actual intercalation: recursive -->
                      <xsl:template name="intersperse-with-zero-spaces">
                      <xsl:param name="str"/>
                      <xsl:variable name="spacechars">

                            
                           ​
                      </xsl:variable>

                      <xsl:if test="string-length($str) > 0">
                      <xsl:variable name="c1"
                      select="substring($str, 1, 1)"/>
                      <xsl:variable name="c2"
                      select="substring($str, 2, 1)"/>

                      <xsl:value-of select="$c1"/>
                      <xsl:if test="$c2 != '' and
                      not(contains($spacechars, $c1) or
                      contains($spacechars, $c2))">
                      <xsl:text>​</xsl:text>
                      </xsl:if>

                      <xsl:call-template name="intersperse-with-zero-spaces">
                      <xsl:with-param name="str" select="substring($str, 2)"/>
                      </xsl:call-template>
                      </xsl:if>
                      </xsl:template>

                      </xsl:stylesheet>
                    • Nikolai Grigoriev
                      Hi, ... Two things: 1) my original post contained an error that still persists in your stylesheet: the last character in each text node will be stripped. For
                      Message 10 of 19 , Dec 6, 2001
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                        Hi,

                        > Ah, progress: taking out the mode="insert-zero-spaces" attribute from
                        > the first template gets me strings with embedded nonprintable
                        > characters, which is a lot closer. More to follow...

                        Two things:

                        1) my original post contained an error that still persists in your stylesheet:
                        the last character in each text node will be stripped. For fix, see my previous
                        mail;

                        2) I put it in a separate mode because I thought it should be applicable to
                        text only inside table cells. It is convenient to switch modes in these cases.

                        Regards,
                        Nikolai
                      • barrett808
                        I have Nikolai s code working just right for my purpose, and after some hacking on my instance document, I can get XEP to render it. XEP complains about
                        Message 11 of 19 , Dec 7, 2001
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                          I have Nikolai's code working just right for my purpose, and after
                          some hacking on my instance document, I can get XEP to render it. XEP
                          complains about xml:space, and spuriously complains about fo:page-
                          sequence needing master-name to be declared (it is), also doesn't
                          handle UTF-16 encoding. (Apache FOP complains about many basic FO
                          attributes being not-yet-implemented and produces completely screwed-
                          up output; XSL Formatter doesn't seem to understand zero-width
                          characters at all).

                          But after hacking my document to make XEP happy, what comes out is
                          suboptimal: it appears the zero-width space characters (Unicode 200B)
                          are being rendered as regular spaces. Same with the hair-width char
                          (200A).

                          So it appears I don't have a real solution. :(
                        • dvd@renderx.com
                          ... This is a difference between the obsolete XSL FO C(andidate)R and the current XSL FO Recommendation. In the Candidate fo:page-sequence had attributed named
                          Message 12 of 19 , Dec 8, 2001
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                            >
                            >
                            > I have Nikolai's code working just right for my purpose, and after
                            > some hacking on my instance document, I can get XEP to render it. XEP
                            > complains about xml:space, and spuriously complains about fo:page-
                            > sequence needing master-name to be declared (it is), also doesn't

                            This is a difference between the obsolete XSL FO C(andidate)R and
                            the current XSL FO Recommendation. In the Candidate fo:page-sequence
                            had attributed named 'master-name'. In the final Recommendation it
                            was renamed to 'master-reference'. The phrase 'master-name needs to be
                            declared for' means that it is not declared in the DTD the xml is being
                            validated against, as opposite to be DEFINED in the xml (xsl fo file)
                            itself.

                            The diagnostics means that master-name is NOT DECLARED In the DTD and
                            thus is not allowed in your XSL FO. Upgrade your stylesheets and
                            you'll get rid off the message.

                            > handle UTF-16 encoding.

                            This is not an issue with XEP. Any SAX XML parser may be plugged into,
                            thus just choose one that supports encodings you need.

                            > But after hacking my document to make XEP happy, what comes out is
                            > suboptimal: it appears the zero-width space characters (Unicode 200B)
                            > are being rendered as regular spaces. Same with the hair-width char
                            > (200A).

                            200A and 200b are rendered differently. 200b is just removed from the
                            output. 200b is used internally to mark places where line breaks are appropriate,
                            and if it looked like a space that would be obvious. It is not rendered.

                            David Tolpin
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