如何使用XPath / Xsl将子元素与不同父元素下的同一子元素进行比较？

I need to use xsl/xpath (version 1.0) to do something special (for simplifying, say insert some dummy text) when the value of SupplierId changes. I need to handle 3 variations;I need to use xsl/xpath (version 1.0) to do som