Balisage Paper: Copy-fitting for Fun and Profit

Copy-fitting as estimating

There are multiple, and sometimes conflicting, aspects to the relationship between copy-fitting and profit. For the commercial publisher, there is tension between more pages costing more money and more pages providing a better reading experience or even a better “shelf appeal”, for want of a better term. We tell ourselves do not judge a book by its cover, but we do still sometimes judge a book by the width of its spine when we look at it on the shelf in the bookstore. Copy-fitting, in this first sense, is part of the process of making the text fill the number of pages (the ‘extent’) that has been decided in advance by the publisher. This may mean increasing the font-size, leading, other spaces, and the margins to fill more pages, or it may mean reducing them so that more text fits on a page.

Figure 1: Different approaches to filling pages

The six steps to copyfitting from “How to Spec Type” White are:

However:

Copy-fitting as adjustment

‘Copy-fitting’ as adjustment is now the more common use for the term.

Books

The total number of pages in a book is generally a multiple of 16 or 32, and any variation can involve additional cost:

The role here for copy-fitting (in the second sense) is to ensure that the overall page count is at or close to a multiple of the number of pages in a signature.

Even Print-On-Demand (POD) printing has similar constraints. For example, the Blurb POD service requires that books in “trade” formats – e.g. 6×9inches – are a multiple of six pages Blurb. In a simplistic example, suppose that the document with the default styles applied formats as 15 pages:

Figure 2: Document with default styles and six-page signatures

The (self-)publisher has the choice of three alternatives:

Manuals and other documentation

A manufacturer who provides printed documentation along with their product faces a different set of trade-offs. The format for the documentation may be constrained by the size of the product and its packaging, regulatory requirements, or the house style for documentation of a particular type. A manufacturer may need to print thousands or even millions^[1] of documents. Users expect clear documentation yet may be unwilling to pay extra when the documentation is improved, yet unclear documentation can lead to increased support costs or, in some cases, to fatalities.

Suppose, for example, that the text for a document has been approved by the subject matter experts – and, in some cases, also by the company’s lawyers and possibly the government regulator – and has to be printed on a single standard-size page, or possibly a single side of a standard-size page, yet there is too much text for the space that is available. To let the editorial staff rewrite the text so that it fits the available space is definitely not an option, so it becomes necessary to apply copy-fitting to adjust the formatting until the text does fit. Figure 5 shows an information sheet that was included with the Canon MP830 when sold in EMEA. The same information in 24 languages is printed on a single-sided sheet of paper. Most users would look at the information once, at most. If the information had been allowed to extend to the back of the sheet, it would have considerably increased the cost of providing the information for no real benefit. Some form of copy-fitting was probably used to make sure that the information could fit on one side of the sheet.

Figure 5: Multiple warnings on a single-sided sheet

Multilingual text has other complications. Figure 6 shows two corresponding pages from the English and Brazilian Portuguese editions of the Canon MP830 Quick Start Guide. The same information is presented on both pages. However, translations of English are typically longer than the corresponding English, and this is no exception. The Brazilian Portuguese page has more lines of text on it and, as Figure 7 shows, the font-size and leading has also been reduced in the Brazilian Portuguese page. A copy-fitting process could have been used to adjust the font-size and leading across the whole document by the minimum necessary so that no text overflowed its page.

Figure 6: English and Brazilian Portuguese pages

Figure 7: English and Brazilian Portuguese text

Extensible Stylesheet Language (XSL) 1.1

XSL 1.1 does not address copy-fitting, but it does define multiple properties for controlling aspects of formatting that, if the properties are not applied, could lead to problems that would need to be corrected using copy-fitting:

Figure 8: Orphans and widows

Extensible Stylesheet Language (XSL) Requirements Version 2.0

“Extensible Stylesheet Language (XSL) Requirements Version 2.0" XSLReq2.0 includes:

List of CSS features required for paged media

“List of CSS features required for paged media” (https://www.w3.org/Style/2013/paged-media-tasks) by Bert Bos has a ‘Copyfitting’ section. Part of it is relevant to fitting content into specified pages.

Print & Page Layout Community Group

The Print and Page Layout Community Group developed a series of open-source extensions for XSLT processors so you can run any number of iterations of your XSL-FO processor from within your XSLT transformation, which allows you to make decisions based on formatted sizes of areas.

The extensions are currently available for Java and DotNet and use either the Apache FOP XSL formatter or Antenna House AH formatter to produce the area trees.

To date, stylesheets that use the extensions have been bespoke: writing a stylesheet that uses the extensions has required knowledge of the source XML, and the stylesheet for transforming the XML into XSL-FO is the stylesheet that uses the XSLT extensions.

Figure 10: Balisage 2014 poster (detail)

AH Formatter

AH Formatter, from Antenna House, extends the overflow property. When text overflows the area defined for it, the text may either be replaced or one of a set of properties – including font-size and font-stretch – can be automatically reduced (down to a defined lower limit) to make the text fit into the defined area.

FOP

FOP provides fox:orphan-content-limit and fox:widow-content-limit extension properties for specifying a minimum length to leave behind or carry forward, respectively, when a table or list block breaks over a page.

Error condition XSLT

The individual XSLT file for an error condition consists of an XSLT template that matches on a node with that specific error. The result of the template is an XML node encoding the error condition and its location. The details of how to represent the information are not part of the template (and are still in flux anyway).

<xsl:template
    match="at:LineArea[ahf:is-page-end-hyphen(.)]"
    mode="ahf:errors">
  <xsl:param name="page" as="xs:integer" tunnel="yes" required="yes" />
  <xsl:param name="x" as="xs:double" tunnel="yes" required="yes" />
  <xsl:param name="y" as="xs:double" tunnel="yes" required="yes" />

  <xsl:variable
      name="x"
      select="if (exists(@left-position))
                then $x
                     + ahf:length-to-pt(@left-position)
               else $x"
          as="xs:double" />
  <xsl:variable
      name="y"
      select="if (exists(@top-position))
                then $y
                     + ahf:length-to-pt(@top-position)
              else $y"
      as="xs:double" />
  <xsl:sequence
      select="ahf:error('page-end-hyphen', $page, $x + ahf:length-to-pt(@width),
          $y - ahf:length-to-pt(at:TextArea[last()]/@font-size) div 2)" />

  <xsl:next-match />
</xsl:template>

<xsl:function name="ahf:is-page-end-hyphen" as="xs:boolean">
  <xsl:param name="line-area" as="element(at:LineArea)" />

  <xsl:sequence
      select="empty($line-area/following-sibling::at:LineArea) and
              $line-area/at:TextArea[last()][@text[ends-with(., '-') or ends-with(., '‐')]] and
              empty($line-area/ancestor::at:ColumnReferenceArea[1]/following-sibling::*)" />
</xsl:function>

Formatting error XML

The XML for reporting errors is essentially just a list of errors and their locations. Again, this is still in flux.

<errors>
   <error code="max-hyphens" page="1" x0="523.2752" y0="583.367"/>
   <error code="page-end-hyphen" page="2" x0="523.2760000000001" y0="740"/>
   <error code="paragraph-widow" page="6" x0="94.462" y0="418"/>
   <error code="page-end-hyphen" page="7" x0="523.2760000000001" y0="740"/>
   <error code="page-sequence-widow" page="8" x0="72" y0="72"/>
</errors>

PDF error report

The error XML can be processed to generate a report. It is, of course, also possible to augment the Area Tree XML to add indications of the errors to the formatted result, as in the simple example below.

Figure 12: Error report PDF (detail)

Copy-fitting instructions

The copy-fitting instructions consist of sets of contexts and changes to make in that context. The sets are applied in turn until either the current formatting round does not generate any areas or the sets are exhausted,in which case the results from the round with the least number of errors are used. Within each set of contexts and changes, the changes can either be applied in sequence or all together. Like the rest of the processing, the XML format is still in flux.

<copyfitsets>
  <copyfit use="all" name="copyfit1">
    <match role="chapter-drop" />
    <use height="25%"/>
    <match font-family="'Source Serif Pro', serif" font-size="11pt" />
    <use font-size="10.5pt" line-height="13.5pt"/>
  </copyfit>
  <copyfit use="first">
    <match role="chapter-drop" />
    <use height="20%"/>
    <match font-family="'Source Serif Pro', serif" font-size="11pt" />
    <use font-size="10.5pt" line-height="13.5pt"/>
  </copyfit>
</copyfitsets>

When the XSLT extensions from the Print & Page Layout Community Group are used, the changes instruction indicates a range of values. The XSLT initially uses the .start value and, if errors are found, does a binary search between the .start and .end values. Iterations continue until no errors occur, the maximum number of iterations is reached, or the difference between iterations is less than the allowed tolerance.

<copyfitsets>
  <copyfit condition="page-sequence-widow">
    <match  font-size="11pt" />
    <use line-height.start="14pt" line-height.end="13pt" />
  </copyfit>
</copyfitsets>

The copy-fitting instructions are transformed into XSLT that is executed by the XSLT processor, similarly to how Schematron files and XSpec files are transformed into XSLT that is then executed.