In margin pledging, you grant the broker the right to sell your pledged shares if you fail to meet a margin call (a demand for additional funds because of falling market values). This is done through CDSL (Central Depository Services Limited) authorization. It protects the broker from financial losses in case you cannot repay the borrowed margin. CDSL authorization is important because: 

• It allows CDSL to confirm that you own the shares you want to pledge.
• It enables secure transfer of pledged shares from your demat account to your pledge account
• It ensures that your pledged shares are used only for margin pledging. If the broker defaults, CDSL safeguards your ownership and protects you from the unauthorized sale of your shares.
• It ensures that you and your broker adhere to regulations.