To access past data (rotation, price retracement, etc) for completed leg information, the easiest way is to use the flex statistics options of the ZigZag Oscillator tokens, as highlighted in this video :

https://www.linnsoft.com/videos/zzo-flex-stats

For example, to get the “components” (i.e. tokens) needed to detect the AB=CD conditions harmonic pattern (and detect such a harmonic pattern whenever the pivot D is confirmed), the following ZZO tokens parameter provides the rotation in ticks of the past AB and CD legs

This way, a custom indicator with a syntax such as 

100*ABS(ZZO_AB_TICK-ZZO_CD_TICK)/ZZO_CD_TICK

returns the %deviation between both AB and CD legs

For the other AB=CD harmonic pattern rules, one needs to add

• Conditions around the ZZO flex statistic tokens corresponding to the BC and CD price retracement value (I also make sure AB retracement is above 100, i.e a trend is already in place). A C#2 margin is used to define the acceptable interval of both Fib Retracement ratios 
• a filter so that all conditions are tested whenever the pivot D is confirmed, ie whenever the overall ZZ retracement criteria is hit. For the bullish case, this bar can be detected with the signal ZZO_CFD_PRICE> ZZO_CFD_PRICE.1 with the ZZO tokens set up as the Confirmed Pivot Price. To cover both bullish and bearish case, one can use PNZ(CI) with the PNZ token returning the sign of the following Custom Indicator 

(ZZO_CFD_PRICE<ZZO_CFD_PRICE.1)+(ZZO_CFD_PRICE>ZZO_CFD_PRICE.1)*(-1)

A full chart definition will be available shortly.