Let's start with defining what a plan is. A plan is defined as a sequence of actions that need to be applied to reach some pre-defined goal, improving the current position or situation. A plan can be seen as a recipe for improving an environment, growth, or preservation of values like knowledge, wealth, ethical values, economy, etc.
To reach a solution, sometimes, a single decision can be considered. However, most real-world scenarios involving decisions are more complex and require a sequence of decisions. Each decision (or series of decisions) that we put into action causes a change in the problem we are trying to solve, our environment or ourselves.
By the same logic that we define a plan as a sequence of actions, we define a decision-plan as a sequence of a decision taken to achieve a solution to a problem or some aspect of the environment and yourself (or AI machine/operator) within it.
Decisions or decision plans that we consider but are not converted to actions are simulations or research that can be converted to knowledge. Simulations and analysis converted to knowledge should support future decisions, which supports future activities.