function changePreviewField( sField, sValue )
{
	var oPreview = document.getElementById( "tafpreview" );
	if ( oPreview )
	{
		var aSpan = document.getElementsByTagName( "span" );
		for ( var i = 0; i < aSpan.length; ++i )
			if ( aSpan[ i ].className.match( new RegExp( sField ) ) )
				aSpan[ i ].innerHTML = sValue;
	}
}