Exhaustion gaps may occur at the top or bottom of a formation when trends change direction in an atypically quick manner. There is no consolidation next to the broken trend line: The trend reversal is very sharp through a bullish move, looks a lot like a measurement gap.
From a technical point of view, runaway, or measurement, gaps are special gaps that occur within solid trends. They are known as measurement gaps because they tend to occur about midway through the life of a trend. Thus, if you measure the total range of the previous trend and extrapolate it from the measurement gap, you can identify the end of the trend and your price objective. Since the velocity of the move should be similar on both sides of the gap, you also have a time frame for the duration of the trend.
Common gaps have the least technical significance of all the types of gaps. They do not indicate a trend start, continuation, reversal, or even a general direction of the currency other than in the very short term. Common gaps tend to occur in relatively quiet periods or in illiquid markets.
Breakaway gap formations occur at the beginning of a new trend, usually at the end of long consolidation periods. They may also appear after the completion of some chart formations that tend to act as short-term consolidations. Breakaway gaps signify a brisk change in trading sentiment, and they occur on increasingly heavy trading.
Also known as a trading range (or congestion), the rectangle formation reflects a consolidation period. Upon breakout, it is likely to continue the original trend. Its failure will change it from a continuation to a reversal pattern. This pattern is easy to spot, as it can be considered a minor side-ways trend.