IS0 91-1:1992 refers to petroleum measurement tables published by the American Petroleum Institute (API, USA), the American Society for Testing and Materials (ASTM, USA) and the Institute of Petroleum (IP, UK) and subsidiary documents, correcting the printing errors in these publications, based on reference temperatures of 15 °C and 60 °F.

The standard reference temperature for petroleum measurement adopted in IS0 5024 is 15 °C, and should be used for international trade. However, it is recognized that its use is not yet universally accepted and references to tables based on 60 °F have therefore been included in IS0 91-1:1992 and tables based on 20 °C are covered in IS0 91-2.