As you already know, OKR stands for Objectives and Key Results. The Objective tells you where you want to be by the end of a given timeframe and Key Results give you feedback as to whether or not you're getting there (GPS). In Perdoo there's a third element that we integrate into the process, Initiatives.
To achieve certain results, you need to take action - Key Results won't magically move, they need to be pushed. Initiatives are all those projects you believe will help achieve those desired outcomes. In other words, Initiatives are hypotheses that are validated through Key Result progress.