I will admit, it's a bit sneaky but afaik it's within the rules \:\/

 Code:
; begin KiXgolfUDF
;
;!
Function WFP($t)
dim $, $c

$ = CreateObject('Microsoft.XMLDOM')
$.load($t)

$t = 'non '
$wfp = iif(val($.firstChild.nodetype) + $.parseError.errorCode<7,$t,'')+'well-formed'

For Each $ in $.getElementsByTagName('*')
	For Each $c in $.childnodes
		if $.tagname = $c.tagname
			$wfp=$t+$wfp
EndFunction
;!
;!
; end KiXgolfUDF



 Code:

KiXtart
KiXtart Version  = 4.60
KiXGolf Script   = kixgolf_wfp.KIX

Computer
OS               = Windows Vista Business Edition
CPU              = Intel Pentium Model 15
Speed            = 2194 MHz
Memory           = 2038 MB

KiXGolf Scoring Engine
Scoring Engine   = 3.3

KiXtart Golf Score
Tournament       = A Well-Formed Problem
Processing Start = 2008/12/20 14:26:43.200
Processing End   = 2008/12/20 14:26:43.501
Duration         = 0000/00/00 00:00:00.300
KiXGolf Score    = 261
 
Thank you for participating in KiXtart Golf!
_________________________
The Code is out there