S. 172: Shipping business-Non-residents-Certificate issued by Inland Revenue Authority of Singapore stating that income derived from operation of ships in international traffic at Indian port would be governed by article 8 and not article 24 and was taxable in Singapore-Contents of certificate considered by court in earlier decision-Held, in absence of any other material on record to demonstrate veracity of certificate was doubtful Tribunal could not have restored matter to Assessing Officer merely on suspicion and doubts contrary to findings arrived at by this court in earlier decision-Assessment order passed consequent to remand quashed and set aside-DTAA-India-Singapore [S. 172(2),260A, Art, 8,24]