The reason that these size standards vary is due to the fact that many national standards for measurement were developed before the establishment of The International Organisation for Standardisation (yawn), It was formed after the second world war with hopes that nations would adopt the measuring system of mondopoints. However, as with most things the respective nations and manufacturers have been hesitant to make any significant changes to national standards. However, an increasing importance of international trade and e-commerce has prompted many manufacturers to change sizing standards. Many different companies have adopted either US or European standards of footwear measurement.