settings

I've been messing with some settings within my charting platform (Tradestation) and trying to determine which to use.  There's a setting for building intra-day bars that seems to affect only charts greater than 15-minutes in length.  The options are "Natural Hours" and "Session Hours".

Below is what a 130-minute chart looks like using one or the other settings.  Of course, a 130-minute bar should only contain 3 bars per day...

It appears as though "Natural Hours" builds the first bar of the day differently than it does the remaining bars.

Below is a 65-minute chart.  The "Natural Hours" selection builds a 10-minute bar first, followed by 65-minute bars and ending with a 55-minute bar.  Not only that, but the Natural Hours Open is $143.89 while the Session Hours Open is $144.09.

Talking with tech support at Tradestation they explained (though he at first didn't know the difference and seemed to have needed to pull out the manual to find out) something to the effect that each index opens slightly different and so the "Session Hours" may begin with a time, while the "Natural Hours" begin with a first print.  I'm going to have to look further into this topic.  But if you see a disparity in my charts this is the reason.