Back	Standard: http://www.w3.org/TR/xslt#element-value-of

<value-of> : select

Standard excerpt:

The required select attribute is an expression; this expression is evaluated and the resulting object is converted to a string as if by a call to the string function. The string specifies the string-value of the created text node. If the string is empty, no text node will be created. The created text node will be merged with any adjacent text nodes.

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