Standard Each standard described in section 321 shall include, at a minimum, the following: (1) Workplace violence prevention plan Not later than 6 months after the date of promulgation of the interim final standard under section 321(a), or 18 months after the date of enactment of this Act in a case described in section 321(a)(5), a covered employer shall develop, implement, and maintain an effective written workplace violence prevention plan (in this section referred to as the Plan ) for covered employees at each covered facility and for covered employees performing a covered service on behalf of such employer, which meets the following: (A) Plan development Each Plan— (i) shall be developed and implemented with the meaningful participation of direct care professionals, other employees, and employee representatives, for all aspects of the Plan