Go to standardXPath function: string normalize-space (string?)
Standard excerpt:
The normalize-space function returns the argument string with whitespace normalized by stripping leading and trailing whitespace
and replacing sequences of whitespace characters by a single space. Whitespace characters are the same as those allowed by
the S production in XML. If the argument is omitted, it defaults to the context node converted to a string, in other words
the string-value of the context node.
Examples (xslt:xml):
Interactive xlab: [xsl:value-of] [xsl:template]