Registration of Document.

• By registering a document, it get a legal entity. a registered document is accepted as an eveidence in the court of law. 
• it creates rights and liabilities on the parties executing and registering it. 
• it creates genuineness and authencity about that registered document. 

under the registration act, a document registered with the registrar before him is of much value the same can be use in future and either of the parties cannot deniey that

Section 17 of the Registration Act deals with documents requiring mandatory registration. Any document which creats or transfers interest, right or title to immovable property requires mandatory registration. The document cited by you is one such document.

Strictly speaking the Registration act does not imply that any documemnt needing mandatory registration if not registered becomes invalid, or void. such document, as long as it is otherwise valid as per the requirements of Contract Act, remains valid and binding on parties. The consequence of non-registration in that case will be that this document cannot be relied upon by the litigating party and it will not be admissible in evidence for the main transaction, except for ancilliary or incidental issues. However, the opposite party can still rely on this document. For ex. if you buy a property and the sale deed is not registered, you will not be able to rely upon that document for main purpose, but your opponent can still produce this as evidence.

Registration affords authenticity to a document. A registered document evidencing a particular transaction will always be preferred to a non-registered one.