Understanding DA and Salary Components for Private Industry Employees: What's Required?

Does DA apply to private industry employees?
Does DA apply to private industry employees (other than government)? As per statutory requirements, what are the salary components for private industry employees?

Dearness Allowance, which changes according to the cost of living index, is a mandatory component of salary. However, it is not necessary to have DA as a separate component provided your total salary is more than the statutory minimum salary fixed by the government, and you increase it periodically considering the increase in the cost of living indices.