Lock-out notice requirements mandate Form-XII service, public display, and electronic intimation to labour authorities. Notice of lock-out must be issued in Form-XII by the employer to registered Trade Unions by speed post or electronically, with electronic copies to the conciliation officer, Chief Labour Commissioner (Central), and the Ministry. The notice must be prominently displayed at the industrial establishment and may also be posted on the designated portal. If a lock-out notice is given to any employee, the employer must inform the conciliation officer and Chief Labour Commissioner (Central) electronically within five days.