Requirements Revisited

It is extremely rare that all of the requirements have been defined before the construction phase. In fact, it is not even reasonable to expect that the requirements will be 100% complete before starting implementation. The reason is because unless all of the details are known—and nailing down the details is what you do in the construction phase—it is impossible to have all of the requirements carved in stone. So in addition to design, implementation, and testing, there will inevitably be a continuing amount of requirement work that needs to be addressed. This includes refactoring and clarifying existing requirements as well as developing new requirements. Common sources for new requirements that show up in the construction phase are as follows: