Sammy, I think it just means that the top of the last white box = 573.75.
If you make the box size = 15, then that "number that you refer to" becomes 600, which is the top of the last white box tonight, while the close is shown as 607.45.
Since this is just Monday, the weekly value is meaningless till about 3:30 on this coming Friday.
Since Renko does not plot time factor, using an hourly, daily, or weekly "Update" value can change the whole look and smell of the chart. It is kinda hard to get your arms around.
Lookin at today (Monday)on a weekly chart is like lookin at the first 5 minutes of an hourly bar on a 60" candlestick chart.
On a weekly chart, today's blocks could be totally changed by Friday.
On a daily chart, today's blocks would be locked in, or could not change.
If you setup the Renko on your QT charts, there is no way to pick an update period -- QT appears to update the chart constantly, taking only brick size into account.
Hope this does not just make it all the more confusing,
bobjack
