"It is not the strongest of the species that survives, nor the most intelligent, but rather the one most responsive to change." Charles Darwin In UBL you have the opportunity to react on changes and given requirements by customizing the existing UBL documents following certain rules.This "Customization Area" of ubl.xml.org allows you to present and discuss your customizations of UBL done or planed with others in order to reach the highest level of interoperability by re-using existing customizations and to avoid uncontrolled growth of potential wrong customizations.