Most DocBook list elements take an optional title element to let you label a list. The title appears before any list items and before any prolog elements that appear at the beginning of a list.

For print output, the title is processed in mode="list.title.mode", with the title as the context node. By default, that mode just calls the template named formal.object.heading with the parent list element as its object parameter. The result is that any list title formats like a figure title (without a number label). But if you want to customize how one kind of list title formats, you can create a template in that mode matching on that list type.

Customizing orderedlist titles for print:
<xsl:template match="orderedlist/title" mode="list.title.mode">
  <fo:block font-size="14pt" font-weight="normal"
            xsl:use-attribute-sets="normal.para.spacing">
    <xsl:apply-templates/>
  </fo:block>
</xsl:template>

For HTML output, you should copy the formal.object.heading template from html/formal.xsl to your customization layer and modify it as needed. In that template, the context node is the list element, not the title element. You can make the processing conditional on the list type by using an xsl:choose statement as follows:

...
<xsl:choose>
  <xsl:when test="$object/self::orderedlist">
    <!-- processing steps for orderedlist -->
  </xsl:when>
  <xsl:otherwise>
    <!-- processing steps for other formal object headings -->
  </xsl:otherwise>
</xsl:choose>