XSLT Stylesheet: Changing text to upper case

XSLT 2.0 has fn:upper-case() and fn:lower-case() functions. However in case you are using of XSLT 1.0, you can use translate():

<xsl:template match="/">
  <xsl:variable name="smallcase" select="'abcdefghijklmnopqrstuvwxyz'" />
  <xsl:variable name="uppercase" select="'ABCDEFGHIJKLMNOPQRSTUVWXYZ'" />
  <xsl:value-of select="translate(doc, $smallcase, $uppercase)" />
</xsl:template>

You can use the translate() function in XSLT 1.0:

<xsl:value-of select="translate(//some-xpath,
                                'abcdefghijklmnopqrstuvwxyz',
                                'ABCDEFGHIJKLMNOPQRSTUVWXYZ')" />

If you're lucky enough to have access to XSLT 2.0, you can use the upper-case() function:

<xsl:value-of select="upper-case(//some-xpath)"/>

See the XPath function reference page for more details.