[[Image:Specification and Levels of Development.jpg|thumb|360px|Systems engineering model of Specification and Levels of Development. During systemDuringtem development a series of specifications are generated to describe the system at different levels of detail. These program unique specifications form the core of the configuration baselines. As shown here, in addition to referring to different levels within the system hierarchy, these baselines are defined at different phases of the design process.Note: There is one minor (and ironic) typo in the image above. SI&T is "System Integration and Test" not "System Integration and Text". ]]
