Software Engineering

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CHAPTER 9 
Software Requirements Management
regression when assessing the effort required for the incorporation of a change 
into a partially complete architecture description. Original tasks may need to be 
revised, rescheduled, or eliminated altogether to accommodate the change. Every 
change will involve some rework that affects established architectural design doc-
umentation, reanalysis of previous architectural decisions, and additional analysis 
to incorporate the proposed change into the existing architectural framework. This 
potentially will result in progress being suspended while a change is assimilated 
into the software architecture to establish a new basis for proceeding toward an 
architectural conclusion.
In the final analysis, change proposals should not be considered for adoption 
once the product architecture is nearing completion. Initial planning estimates 
for the architecture definition phase of development should incorporate adequate 
resource and schedule leeway to account for requirements changes. With suffi-
cient flexibility planned into the early phases of development, a number of critical 
change proposals may be accommodated. This preplanned schedule margin should 
be included in every work package, as a buffer, to ensure the achievement of the 
critical design review (CDR) milestone and transition to software implementation.