Dear Sir, while Notification No.42/2012 grants conditional exemption to services received in SEZ, Nofn.25/2012-ST grants exemption to services by way of construction, erection, commissioning, or installation of original works pertaining to an airport, port or railways, including monorail or metro. Thus, the latter covers certain specific services only. Further, the term "port" covered in therein is to be read in terms of Section 65B (38) "port" has the meaning assigned to it in clause (q) of section 2 of the Major Port Trusts Act, 1963 (38 of 1963) or in clause (4) of section 3 of the Indian Ports Act, 1908; (15 of 1908). The distinction may therefore be taken note of.