Deduction of Salary U/S 10(2)(xi) - Koi Baat Hai?

Dude I'm literally dying here, 2 am and taxation law is still killing me. 'Papa ki chidiya ne papa ko itna confusion diya ki judge ne khud khade ho jaa kar suna.' Just kidding, Papa ne case ke liye yeh argument use kiya tha. Seriously though, U/S 10(2)(xi) ke under salary ki deduction kaise hoti hai, yeh pehla baar me main samjh nahi raha hoon. Pehle to me samajhne ki koshish kar raha hoon ki salary deduction ki limit kya hai, phir uske under deductions kaise hoti hain. U/S 10(2)(xi) ke under jo salary deduction hoti hai, woh exempt hain, ya phir exempt nahin.