13. …… K.B. Saha and Sons Private Limited v. Development Consultant Limited, (2008) 8 SCC 564……This Court then culled out the following principles:-

21. From the principles laid down in the various decisions of this Court and the High Courts, as referred to hereinabove, it is evident that:-

1. A document required to be registered is not admissible into evidence under Section 49 of the Registration Act.

2. Such unregistered document can however be used as an evidence of collateral purpose as provided in the Proviso to Section 49 of the Registration Act.

3. A collateral transaction must be independent of, or divisible from, the transaction to effect which the law required registration.

4. A collateral transaction must be a transaction not itself required to be effected by a registered document, that is, a transaction creating, etc. any right, title or interest in immoveable property of the value of one hundred rupees and upwards.

5. If a document is inadmissible in evidence for want of registration, none of its terms can be admitted in evidence and that to use a document for the purpose of proving an important clause would not be using it as a collateral purpose.

To the aforesaid principles, one more principle may be added, namely, that a document required to be registered, if unregistered, can be admitted in evidence as evidence of a contract in a suit for specific performance.