XML-TEI How to call two attributes

Question

I'm working with poetry and I want to give to every verse an own ID that mixes the number of the poem and the number of the verse.

Header:

  <?xml version="1.0" encoding ="UTF-8" standalone ="no" ?>
    <TEI xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
      <teiHeader>
        <fileDesc>
          <titleStmt>
            <title n="013">13</title>

Verses:

<lg>
    <l n="01"></l>
</lg>

I want to create an xml:id attribute for <l> like p013-v01 (poem 13, from n@title; verse 1 from n@l). Is there any way to do it automatically for every single line?

The purpose of this is to compare versions and editions of the same poem. I was told to do this, but to be honest I'm not sure of the utility of this xml:id attribute. I hope you can help me. Thanks!

Answer 1

    <xsl:template match="l">
       <xsl:variable name="id-num" select="concat('p', ancestor::TEI/descendant::title/@n, '-v', ./@n)"/>
       <l id="{$id-num}">
          <xsl:attribute name="n"><xsl:value-of select="@n"/></xsl:attribute>
          <xsl:apply-templates/>
       </l>
    </xsl:template>

The id-value is the result of a concatenation of literal text strings and two attribute values.