True Edge
Typically with a high low count, one will determine the true count by dividing one's running count by the number of decks remaining. Then one determines your betting ramp by detemining the percent advantage one has for each true count of one. It just happens that with the high low count, there is approximately .5% advantage for each plus 1 true count. (remember that when you start at the top of a 6 deck game you will be starting with a negative advantage and the amount of disadvantage will be based upon the rules of the game. )
Ok, now move on to Synders thought process - he prefers to determine the actual percent advantage right off the bat and calls this True Edge. The percent advantage for the hi low count will be the running count divided by the number of half decks left. Remember if you decide to use this method, one needs to adjust your strategy tables to reflect the true count per half deck or in Synder's terminolgy the true edge.
With the Zen count which is a level two, the true edge is the running count divided by quarter decks.
Hope this helps.