XSL comparison ignore case

Hi,How to do string comparison in XSL by ignoring case.test="($pr= 'yes')I want this conditon return true even if pr is Yes or YES or YEs.
[168 byte] By [Sheni_a] at [2007-11-27 9:56:20]
# 1
upper-case(string)orlower-case(string)
yue42a at 2007-7-13 0:26:27 > top of Java-index,Enterprise & Remote Computing,Enterprise Technologies...