Shift Assignments When an opening occurs in a shift assignment in an appropriate work group at a location, preference shall be given to employees within the classification who possess the training, ability and any required special qualifications to perform the work required, on the basis of seniority. In the event that no employee desires a shift assignment, employees shall be selected in order of inverse seniority. This provision shall not apply to necessary training assignments. This provision shall not in itself alter the practice of rotating shifts where such practice presently exists. No employee who has a regular shift assignment on the effective date of the Agreement shall be involuntarily displaced from such shift assignment as a result of this Article.