Sanjiv Khanna, J.

1. This common judgment will dispose of the aforementioned 11 writ petitions in which identical and similar issues arise for consideration. The petitioners herein have challenged and prayed for quashing of Explanation to Notification No. 15/2004-ST dated 10th September, 2004 and Notification No. 18/2005-ST dated 7th June, 2005 and in Notification No. 1/2006-ST dated 1st March, 2006, the challenge is with respect to column 4 entries at S. No. 5, 7 and 10. In some writ petitions, assessment orders have been passed and appellate proceedings have been initiated. However, in Writ Petition No. 4107/2008 by G.D. Builders, Writ Petition No. 5046/08 by Unitech Limited, Writ Petition Nos. 401/2009, 4057/2010 & 6658/2010 by Simplex Infrastructure Ltd. and Writ Petition Nos. 4187/2008 and 5646/2010 filed by Vistar Construction Pvt. Ltd., show cause notices have been issued and the proceedings are still pending before the original authority. In Writ Petition No. 4127/2008 filed by Clarion Properties Ltd. and Writ Petition No. 4658/2008 filed by Vipul Limited, notice for appearance of furnishing of documents/reply has been given and even show cause notice has not bee