Severance pay when a company moves for employees who don't move?

I understand that after 120 days a business basically must pay one months severance (with a few exceptions crimes etc) and after longer time periods more severance pay.

What happens if an employee is given one plus month notice of the business move and invited to move with the company (moving expenses paid plus bonus etc) and the employee does not want to move - so they lose their job?

Reading the labor law it seems like there is a special 50% severance pay - is this in addition to or instead of the regular severance pay?

The severance pay in this case is not less than 50% of the normal severance due rather than the full amount

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