<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>Dispensing closure incorporating a product-flow controlling valve within the orifice. Product will not dispense from the package until sufficient squeezing pressure is applied to the flexible container to cause the valve to open.</n0:def-definition><n0:def-source>FDA</n0:def-source><n0:attr>Stability</n0:attr></n0:ComplexDefinition>