what you want to do seems a bit strange. xml (with some exceptions) is used to store data (statically store, like in a DB).
any condition would need someone/something (that someone is usually called "parser") that actually decides if the condition is fulfilled or not. an xml parser doesn't do that.
in your case I recommend using a script that processes an input giving you the desired xml file.
- xslt (needs xml, returns xml or text)
- any programming language
for the case of xslt your “weapon” of choice is a conditional XPath expression, e.g.
- <xsl:template match="element[fld_Country='Canada'][fld_City='Toronto'][fld_Member='1']">
-
// note that the expression depends on your input xml
-
<xsl:text>bla bla blubb</xsl:text>
-
</xsl:template>
in any case I recommend reading a tutorial first, if you're not accustomed to the language you want to use.
XSLT tutorial
if you encounter any problems post back so we can help you getting it right.
regards