Quote:

so, what's wrong with the pipe-character?
doesn't it write null to the regvalue?

No, for two reasons. First, two pipes together "||" are interpreted as a pipe character in the data rather than a null field.

Second, have you tried using Regedit to add a null entry to the value? It removes it and states that null values are not allowed in REG_MULTI_SZ strings.

You *can* write them. I've done it using StdRegProv and SetMultiStringValue along with my binary data UDFs.

The problem is that the values need to be (sort of) UNICODE.

I got part way through writing the ASCII -> UNICODE conversion stuff, but "real work" has intervened and as this is not something I need right now I have had to drop it.

If anyone would like to pick it up and complete it, here is what I have so far...
Code:

Break ON
$=SetOption("Explicit","ON")
$=SetOption("WrapAtEOL","ON")
 
udfAppendMultiSZ(".","HKCU","Software\KiXtart\Testing","RMSZKEY","fooBAR")
If @ERROR "ERROR: " @ERROR ": " @SERROR EndIf
 
Exit @ERROR
 
Function udfAppendMultiSZ($sComputer,$sHive,$sKey,$sValueName,$aValues)
	Dim $iResult
	Dim $aOldValues
	Dim $iHiveID
	Dim $oReg
	Dim $iIndex
 
	Select
	Case $sHive="HKCU" or $sHive="HKEY_CURRENT_USER"
		$iHiveID=&80000001
	Case $sHive="HKLM" or $sHive="HKEY_LOCAL_MACHINE"
		$iHiveID=&80000002
	Case "Default"
		Exit 1
	EndSelect
 
	$aOldValues=ReadValue("\\"+$sComputer+"\"+$sHive+"\"+$sKey,$sValueName)
	If @ERROR Exit @ERROR EndIf
	
	If VarType($aValues) & 8192 $aValues=Join($aValues,"|") EndIf
	If $aOldValues<>"" $aValues=$aOldValues+"|"+$aValues EndIf
 
	$aValues ?
	
	$oReg=GetObject(
		"winmgmts:{impersonationLevel=impersonate}!\\"+
		+$sComputer
		+"\root\default:StdRegProv")
	If @ERROR Exit @ERROR EndIf
	$aValues=Split($aValues,"|")
	For $iIndex=0 to UBound($aValues)
		$aValues[$iIndex]=ASCIItoUNICODE($aValues[$iIndex])
	Next
	Exit $oReg.SetMultiStringValue($iHiveID,$sKey,$sValueName,$aValues)
 
EndFunction
 
; Convert an ASCII string to a UNICODE string
Function ASCIItoUNICODE($s)
	Dim $oStream,$adTypeBinary,$adTypeText
 
	$adTypeBinary=1
	$adTypeText=2
 
	$oStream=CreateObject("ADODB.Stream")
	If @ERROR Exit @ERROR EndIf
 
 
	$oStream.Type=$adTypeBinary
	$oStream.Open
 
	;$oStream.Write(udfIntToByte(255))
	;$oStream.Write(udfIntToByte(254))
	While $s <> ""
		$oStream.Write(udfIntToByte(Asc($s)))
		$oStream.Write(udfIntToByte(0))
		$s=SubStr($s,2)
	Loop
	; Write end of string sentinel
	$oStream.Write(udfIntToByte(0))
	$oStream.Write(udfIntToByte(0))
	$oStream.SetEOS
 
	$oStream.Position=0
 
	$ASCIItoUNICODE=$oStream.Read($oStream.Size)
	$oStream.Close
	"Data type now: " VarTypeName($ASCIItoUNICODE) ?
	Exit 0
 
EndFunction
 
; Convert a single integer to a byte array
Function udfIntToByte($i)
	Dim $oStream,$adTypeBinary,$adTypeText
 
	$adTypeBinary=1
	$adTypeText=2
 
	$oStream=CreateObject("ADODB.Stream")
	If @ERROR Exit @ERROR EndIf
 
	$i=CInt($i) & 255
 
	$oStream.Type=$adTypeText
	$oStream.CharSet="unicode"
	$oStream.Open
	$oStream.WriteText(" "+Chr($i))
	$oStream.Position=0
	$oStream.Type=$adTypeBinary
 
	If $i
		$oStream.Position=$oStream.Size-2
	Else
		$oStream.Position=$oStream.Size-1
	EndIf
	$udfIntToByte=$oStream.Read(1)
	$oStream.Close
	Exit 0
 
EndFunction

The problem is that the ASCIItoUNICODE function converts the string OK, but because it ends up as a BYTE ARRAY the .SetMultiStringValue method rejects the data.

I've also tried reading the data back from the converter using .ReadText with a charset of Unicode. While this returns a string is appears to get set back to an ASCII type which kind of defeats the object.