Session Open Gap Pattern Info

1. IGU - Inside Gap Up, market current open above the prior close inside the prior market high. Price will pullback down to fill the gap after which it may continue down or reverse up again, or the gap is not filled - a gap fill usually quite timely from the open.
2. IGD - Inside Gap Down, market current open below the prior close inside the prior market low. Price will pullback up to fill the gap after which it may continue up or reverse down again, or the gap is not filled - a gap fill usually quite timely from the open.
3. OGU - Outside Gap Up, market current open above prior close/high outside the prior market high. Price will continue up from the open or will pullback to fill the gap to the prior high/close and continue up, or the gap is filled and the market reverses down
4. OGD - Outside Gap Down, market current open below prior close/low outside the prior market low. Price will continue down from the open or will pullback to fill the gap to the prior low/close and continue down, or the gap is filled and the market reverses up

It is thought that Inside gaps are more likely to fill quicker whereas outside gaps may fill at some point if at all.
Note: Gap patterns as any technical analysis are not guaranteed to work everytime out according to the rules, A trader needs to use their discretion of gap analysis to use as a potential filter to trading, with-in context of the overall market structure and cycle and time of day/session.