I have the following xml input and would like to identify the position of the <answer/> element with the 'correct' attribute within the <question/> context and output it as as an integer ( in this case 3).

<question>
   <answer/>
   <answer/>
   <answer eval="correct">
   <answer/>
</question>

Still lacking "count the preceding siblings" method:
 <xsl:template match="question">
   <xsl:value-of
     select="1+count(answer[@eval='correct'][1]
                       /preceding-sibling::answer)"/>
 </xsl:template>