Former Prime Minister Manmohan Singh on Friday gave the GST launch ceremony at Parliament a miss as the Congress boycotted the function, while some constituents of the informal opposition grouping, including the NCP, Samajwadi Party, JD(U) and JD(S), attended the function.JD(S) supremo and former Prime Minister H.D. Deve Gowda, who was one of the special invitees along with Manmohan Singh, attended the function.NCP chief Sharad Pawar also attended the event marking India's transition to a new indirect tax regime Goods and Services Tax (GST).Among the other opposition parties which did not attend the function were the DMK, left parties, RJD and the Trinamool Congress.The Congress had on Thursday decided not to attend the function.