What is a storyline?The storyline refers to the journey on which the deck takes the audience. It should take the audience from Point A (their current mindset) to Point B (your desired outcome).
Think of the storyline as the roadmap for a journey and the PowerPoint deck as the vehicle for taking your audience to your desired destination. Each element of the deck - every page, every exhibit, and each word - should take your audience one step closer to your desired end-state.
What is a "dot-dash" storyline?"Dot-dash" refers to the bullet-point, outline format, where a) main, top-level ideas that drive the storyline are designated with round, dot-shaped bullets and b) 2nd-level, supporting ideas, facts, and exhibits are indented and designated with dashes. These dots and dashes provide the structure around which the PowerPoint deck should be built.
Why are these concepts important?The dot-dash approach allows you to lay out the entire storyline without investing the time to create PPT pages and exhibits. If changes need to be made to the storyline, you can find out before you waste a lot of time and effort.
Think about how long it would take you (and your team) to put together a PowerPoint deck - even a basic, "ghost" deck - to review with key stakeholders, only to receive feedback that the storyline is wrong, some of the pages are off point, and/or you're missing critical content. Not only do you have much rework ahead of you, but you've already lost a lot of time and effort that has now been wasted.
Now consider the same scenario but instead of a deck, you just reviewed a dot-dash storyline outline. You still might have a lot of work ahead of you, but you've learned some valuable lessons about the deck for minimal cost.
For this approach to be effective, it is critical that you develop it and get early feedback from key stakeholders so you give yourself time to course-correct and minimize wasted effort.