The concept of TOD may provide a formula or pattern of the typical structure and configuration of sets of urban uses and spaces with established boundaries supported by various scales and certain levels of urban transportation infrastructure. A certain scale of primary use in TOD usually corresponds to certain scales of secondary use, and the employment opportunities correspond to the matching population of labor. Similar to the concept of neighborhood planning and design, there should be boundaries to define a TOD with a certain composition of mix of uses and configuration.