Besides Dimitre's exact answer, you could use some pattern like in this stylesheet:
With this proper input:
Aanonsen
Fred
Something
Output:
Last Name : Aanonsen
First Name : Fred
Additional Remarks : Something
In XPath 2.0:
string-join(/*/*/*/concat(
(: This is the expression you need :)
replace(name(),
'(\P{Lu})(\p{Lu})',
'$1 $2'),
(: the rest is just to mimic the result :)
' : ',.),
'
')