1. A method of managing data flow in generating profile models for use in optical metrology, the method comprising: creating a project data object; creating a first profile model data object corresponding to a first profile model defined using profile parameters; associating a version number with the first profile model data object; linking the first profile model data object with the project data object; creating at least a second profile model data object corresponding to a second profile model defined using profile parameters, wherein the first and second profile models are different; associating another version number with the second profile model data object; linking the second profile model data object with the project data object; storing the project data object, the first profile model data object, and the second profile model data object; storing the version numbers associated with the first profile model data object and the second profile model data object; storing the link between the first profile model data object and the project data object; and storing the link between the second profile model data object and the project data object.