Establishing the Product Vision and Project Scope

78 Part II Software Requirements Development
One sign that the business requirements are insufficiently defined is that
certain features are initially included, then deleted, and then added back in
later. Vision and scope issues must be resolved before the detailed functional
requirements can be fully specified. A statement of the project's scope and
limitations helps greatly with discussions of proposed features and target
releases. The vision and scope also provide a reference for making decisions
about proposed requirement changes and enhancements. Same companies
print the vision and scope highlights on a poster board that's brought to every
project meeting so that they can quickly judge whether a proposed change is in
or out of scope.
Defining the Vision Through Business Requirements
The product vision aligns all stakeholders in a common direction. The vision
describes what the product is about and what it eventually could become. The
project scope identifies what portion of the ultimate long-term product vision
the current project will address. The statement of scope draws the boundary
between what's in and what's out. That is, the scope also defines the project's
limitations. The details of a project's scope are represented by the requirements
baseline that the team defines for that project.
The vision applies to the product as a whole. It will change relatively
slowly as a product's strategic positioning or an information system's business
objectives evolve over time. The scope pertains to a specific project or iteration
that will implement the next increment of the product's functionality, as shown
in Figure 5-l. Scope is more dynamic than vision because the project manager
adjusts the contents of each release within its schedule, budget, resource, and
quality constraints. The planner's goal is to manage the scope of a specific
development or enhancement project as a defined subset of the grand strategic
vision. The scope statement for each project, or for each iteration or enhancement
in an evolving product, can appear in that project's SRS, rather than in a
separate vision and scope document. Major new projects should have both a
complete vision and scope document and an SRS. See Chapter 10, "Documenting
the Requirements," for an SRS template.