The number of work packages in a project normally increases with project size. Small projects (less than two man years) may have less than ten bottom-level work packages, and large projects (more than twenty man years) more than a hundred. Accordingly, small projects will use one or two levels, medium size projects two to four, and large projects four or five. Medium and large projects may use alphabetic as well as numerical identifiers. New work packages should be defined for new tasks that are identified during a project. The tasks should not be attached to existing, unrelated, work packages. Some projects find it useful to create an 'unplanned work'.
