$Id: lib.xsl,v 1.3 2001/11/28 13:19:36 nwalsh Exp $
Walsh Norman
1999 2000 Norman Walsh

# Library Template Reference

### Introduction

This is technical reference documentation for the DocBook XSL Stylesheets; it documents (some of) the parameters, templates, and other elements of the stylesheets.

This is not intended to be user documentation. It is provided for developers writing customization layers for the stylesheets, and for anyone who's interested in how it works.

Although I am trying to be thorough, this documentation is known to be incomplete. Don't forget to read the source, too :-)

string.subst Substitute one text string for another in a string

    <xsl:template name="string.subst">
    <xsl:param name="string"/>
    <xsl:param name="target"/>
    <xsl:param name="replacement"/>
      ...
    </xsl:template>

The `string.subst` template replaces all occurances of target in string with replacement and returns the result.

xpointer.idref Extract IDREF from an XPointer

    <xsl:template name="xpointer.idref">
    <xsl:param name="xpointer">http://...</xsl:param>
      ...
    </xsl:template>

The `xpointer.idref` template returns the ID portion of an XPointer which is a pointer to an ID within the current document, or the empty string if it is not.

In other words, `xpointer.idref` returns foo when passed either `#foo` or `#xpointer(id('foo'))`, otherwise it returns the empty string.

length-magnitude Return the unqualified dimension from a length specification

    <xsl:template name="length-magnitude">
    <xsl:param name="length" select="'0pt'"/>
      ...
    </xsl:template>

The `length-magnitude` template returns the unqualified length ("20" for "20pt") from a dimension.

length-spec Return a fully qualified length specification

    <xsl:template name="length-spec">
    <xsl:param name="length" select="'0pt'"/>
    <xsl:param name="default.units" select="'pt'"/>
      ...
    </xsl:template>

The `length-spec` template returns the qualified length from a dimension. If an unqualified length is given, the default.units will be added to it.

pi-attribute Extract a pseudo-attribute from a PI

    <xsl:template name="pi-attribute">
    <xsl:param name="pis" select="processing-instruction('')"/>
    <xsl:param name="attribute">filename</xsl:param>
    <xsl:param name="count">1</xsl:param>
      ...
    </xsl:template>

The `pi-attribute` template extracts a pseudo-attribute from a processing instruction. For example, given the PI `<?foo bar="1" baz='red'?>`,

    <xsl:call-template name="pi-attribute">
      <xsl:with-param name="pis" select="processing-instruction('foo')"/>
      <xsl:with-param name="attribute" select="'baz'"/>
    </xsl:call-template>

will return red. This template returns the first matching attribute that it finds. Presented with processing instructions that contain badly formed pseudo-attributes (missing or unbalanced quotes, for example), the template may silently return erroneous results.