Make string lowercase XSLT

How do I convert a string to lowercase in XSLT? I'm really a noob at it, and I kn开发者_运维技巧ow you use the lower-case function, but what's an example of it in use? Do I use <fn:lowercase>StRiNg</fn> or what?

To put you out of your misery, and ignoring protocol regarding duplicate questions,

<xsl:value-of select='lower-case(@prototype)'/>

Check this thread How can I convert a string to upper- or lower-case with XSLT?

Also XPath function reference will be useful http://www.w3schools.com/Xpath/xpath_functions.asp

Ahmed Hashim