a: Narrow spread and wide spread are relative to the other bars on the chart.
b: ultrahigh volume upbar - ether SM are selling into demand - or SM are absorbing supply from the left - When weakness appears it will be on an upbar - but not all upbars are necessarily weak - next bar gives us a clue. If there is a logical resistance line to the left then we need volume to break through but then we look for that volume to be tested if they were bullish. So yes, you are right, it looks like absorption now we want to see testing.
d: low volume downbars show lack of selling pressure - but unless SM respond the price will roll - new sellers (from the herd) can appear at any time for any reason (having a baby, need a new car, who knows) so any imbalance in supply/demand must be acted on quickly, usually 2 - 3 days max if the pros want higher prices - the pros have to keep working the herd to maintain control of an up move - if you stop syphoning a petrol tank half way, you have to start again.
E: notice how all the following bars go up on no demand - the accelerator (volume) is off, but the car is still rolling up the hill - it can't end well (no demand - an up bar on the least volume in 3 bars - especially weak if it is narrow spread and and closes off the high - exact opposite of a no supply test which is a down bar on the lowest volume in 3 bars) and then the final up bar is an upthrust - at the top of a channel.
Also I would add in a downtrend channel we give more weight to the weak bars at the upper trendline than to strong bars at the lower trendline. Conversely in an uptrending channel we give more weight to strong bars at the lower trendline. You can still trade counter trend so long as you are aware you are counter trend.
But your analysis is very good - you've been doing your homework too.
