This document has been prepared as an aid to customers and manufacturers of power transformers in the preparation of specifications for purchasing transformers. Its aim is to highlight some of the important topics that should be considered for includion in an enquiry document. Wherever possible guidance and other practical information about such topics are provided to explain their purpose and significance in transformer enquiries. Clearly it is not possible to address all the issues that may arise. Neither is the document in any way intended to be a complete and applicable specification.