>>>

>>>return typeof loWindow.pageYOffset != 'undefined' ? loWindow.pageYOffset: document.documentElement.scrollTop?
>>> document.documentElement.scrollTop: document.body.scrollTop? document.body.scrollTop:0
>>>

    if (typeof loWindow.pageYOffset != 'undefined') {
>>        return loWindow.pageYOffset;
>>    }
>>    if (document.documentElement.scrollTop) {
>>        return document.documentElement.scrollTop;
>>    } 
>>    return 0;

>
>Yesterday, I came up with this. I do not think that code takes care of all the possibilities. Mine seems to do so:
>
>

>   function PositionTop()
>   {
>      lnOffset=0
>      loWindow=window.parent.oParent
>      if (loWindow.pageYOffset)
>      {
>         lnOffset=loWindow.document.documentElement.scrollTop
>      }
>      else
>      {
>         lnOffset=loWindow.document.body.scrollTop
>      }
>      return lnOffset
>   }
>

My code is functionally identical to the original. Yours is not : If pageYOffset is available you are returning scrolltop rather than pageYOffset.

Thierry gave you the best solution (but ignored your requirement to use more lines :-})