What is the minimum wages considered for PF deduction and PF breakup

Can somebody please help me in this matter?
What is the minimum wages considered for PF deduction? Please provide the pf breakup.
Is employer contribution of PF deducted on min salary of 15,000/-?
Is is mandatory to deduct PF of Rs. 1800/- (12% of 15,000/-) from both employee and employer?

PF should be deducted on basic + DA. Now its not about minimum salary of 15000/-
It reads that if employees have salary less than 15000/-, you have to deduct PF on actual amount of Basic + DA . If someone has salary more than 15000/-, he or she can opt out of PF.
Also, in some cases the employer caps the PF contribution on Max 15000/- for the employees with salary more than 15000/- instead of contributing on whole Basic + DA.
Hope this clarifies your doubt.