Before posting my question I searched through all files and found no instance of 'format="i".'
I'm using DITA-OT 2.2.2. The boilerplate PDF2 plugin has no "if" statement in createToc, and no "format=" either. Here is the code:
<xsl:template name="createToc">
<xsl:if test="$generate-toc">
<xsl:variable name="toc">
<xsl:choose>
<xsl:when test="$map//*[contains(@class,' bookmap/toc ')][@href]"/>
<xsl:when test="$map//*[contains(@class,' bookmap/toc ')]">
<xsl:apply-templates select="/" mode="toc"/>
</xsl:when>
<xsl:when test="/*[contains(@class,' map/map ')][not(contains(@class,' bookmap/bookmap '))]">
<xsl:apply-templates select="/" mode="toc"/>
<xsl:call-template name="toc.index"/>
</xsl:when>
</xsl:choose>
</xsl:variable>
<xsl:if test="count($toc/*) > 0">
<fo:page-sequence master-reference="toc-sequence" xsl:use-attribute-sets="page-sequence.toc">
<xsl:call-template name="insertTocStaticContents"/>
<fo:flow flow-name="xsl-region-body">
<xsl:call-template name="createTocHeader"/>
<fo:block>
<fo:marker marker-class-name="current-header">
<xsl:call-template name="getVariable">
<xsl:with-param name="id" select="'Table of Contents'"/>
</xsl:call-template>
</fo:marker>
<xsl:copy-of select="$toc"/>
</fo:block>
</fo:flow>
</fo:page-sequence>
</xsl:if>
</xsl:if>
</xsl:template>