Window (hydraulic) : The allowable effective fluid density difference between the fracturing pressure and the pressures exerted by a fluid that are needed to control formation flow and the wellbore
George E. King Engineering, 5000 Oilfield Terms: A Glossary of Petroleum Engineering Terms, Abbreviations and Acronyms, US 2010. http://gekengineering.com/Downloads/Free_Downloads /Glossary_of_Petroleum_Engineering_Terms_25_August _2010.pdf, (Oil - Amer) {593}