Input tax credit on OFC ducts and manholes recognised as plant and machinery, hence available under GST law. Ducts and manholes used in optical fiber cable networks are integral to providing telecommunication transmission services and, being neither land, buildings, excluded civil structures, telecommunication towers nor external pipelines, fall within the Explanation's definition of plant and machinery; therefore, availment of input tax credit on such ducts and manholes is not barred by the exclusions to input tax credit.