In Agile, the product roadmap layouts out when the capabilities and features will be deployed for a product. Product roadmaps prioritize significant features or capabilities into a series of releases, with each release building on each other to deliver the overall product vision.

Product roadmaps are, by their nature, high-level. We're talking space station looking down on Earth kind of high level. Looking down from space in zero gravity with the naked eye, you can make out the continents and some prominent mountain ranges, but the rest is too small to be visible. 

Product Owners can align capabilities with releases in the product roadmap based on a "gut feeling" of how big they are or asking the team to provide very imprecise story point estimates for the capabilities. This way, the Product Owner can create a series of releases that are about the same size and align them into a calendar. 

By using inaccurate estimates, the product roadmap is never 100% accurate. This is because the product roadmap doesn't consider that a capability is further refined by splitting it into multiple user stories during release and sprint planning. Each of these user stories, in turn, will get acceptance criteria developed for them that will help better define the solution. It's the law of progressive elaboration - the more you interact with something, the more experience you have. With greater experience, you can predict its behavior.

Using high-level story point guesses - we can't bring ourselves to call them estimates - a Product Owner can group capabilities and total up the story point quest for the release to show the amount of effort estimated for each release. Ideally, trying to create story point guesses for all the new product capabilities would be significantly time-consuming. We recommend assigning story points to releases that are most likely to happen within 3 - 6 months and leave the rest without estimates. A lot changes in 6 months, and planning further out doesn't add much value. We say this because most organizations like to plan out for the entire year to establish budgets, but any planning beyond 6 months is significantly inaccurate.

Although the natural inclination is to take the product roadmap and assign dates to releases, the accuracy of this planning causes false expectations to be set by stakeholders and customers. Express the story point guesses as a range. For example, release 1 has 100 - 200 story points assigned to it. This gives the reader the impression the number is a range or guess. Single numbers imply accuracy.