Definitions for some of the terms used on the AdaptiveTradingSystems.com blog follow.
Proportion of Perfect: Proportion of perfect or proportion of perfect trading is the hypothetical profit made by a trading system or model over a given time period divided by the profit that would have been realized as a result of knowing the future and trading perfectly over the period. The percent of perfect is the proportion of perfect expressed as a percentage. The proportion of perfect is a measure of how efficient the trading signal is.
Proportion of Perfect in Position: Proportion of perfect in position is the proportion of perfect trading measured only when the trading signal has an open position in the market over the given time period. That is, the sum of the profits due to trading the market perfectly are only measured when an open position exists.