“Total number of daily hours the employee must be at work.  All other things being equal, longer core hours imply decreased flexibility of the program” (Golembiewski & Proehl, 1978, p. 838).

Golembiewski, R.T., & Proehl, C.W. Jr. (1978). A survey on the empirical literature on Flexible workhours: Character and consequences of a major innovation.  Academy of Management Review, 3(4), 837-853.