Neither in his letter of resignation nor subsequently is an employee required to indicate the reason or reasons which prompted him to resign, whether he resigns by giving notice or following serious misconduct by the employer.
In addition to announcing the termination, the employee is required to indicate in the resignation letter the period of notice which he must observe vis-à-vis his employer.
The resignation letter must also mention the starting and final date of that notice period, it being understood that the notice begins on the day of notification (and thus of dispatch) of the resignation letter.