math:min() returns the minimum value of a node-set.
To compute the minimum value of the node-set, the node set is sorted into ascending order as it would be using
xsl:sort() with a data type of
number. The minimum value is then the first node in the sorted list, converted into a number.
The node-set whose lowest value is to be returned.
A result tree fragment representing the lowest valued node's numeric value as a string.