The reason he skips the opening bar or half bar is that it takes a little time for the signal to reach an equilibrium or stabilize. The open is apparently too unstable for this type of an indicator. Also he favored natural hour bars that end with the little hand straight up on the clock. Delaying the start until 10AM EST achieves that goal although there are other ways to achieve it and I'm not sure it's just the first 30 minutes of the session that are excluded. For instance TS has a switch for natural hour bars that adjusts to the hourly close for hourly bars even if the initial bar starts on the half hour.
I believe he originally was experimenting with NA for Net Advancing issues. I thought that meant advancing minus declining issues. That might be different than the version he released as oddball but NA is what he called it prior to oddball. I always thought it was the same thing and he just changed the name.
Market Data 
Markets 
AI
