Implementation Shortfall Benchmark Price and Decision Price

The book uses 3 different prices: Benchmark Price, Decision Price and Relevant Decision Price

I understand the difference between Decision Price and Relevant Decision Price, but how is the Benchmark price different from Decision price ?

Benchmark price is the price the first time you decided that you wanted to buy or sell.

Benchmark price is the same as decision price.

Correct me if I am wrong.

that is what i understand it to be

there is a benchmark price (decision price) and then there is a relevant benchmark price (used for the realized p&l calcs). Its a little confusing. work throught an example and you’ll get the drift.