Licensing
Microsoft regulates the appearance of the Windows key logo picture with a specially crafted license for keyboard manufacturers ("Microsoft Windows Logo Key Logo License Agreement for Keyboard Manufacturers"). With the introduction of a new Microsoft Windows logo, first used with Windows XP, the agreement was updated to require that the new design be adopted for all keyboards manufactured after September 1, 2003. However, with the release of Windows Vista, Microsoft published guidelines for a new Windows Logo key that incorporates the Windows logo recessed in a chamfered lowered circle with a contrast ratio of at least 3:1 with respect to background that the key is applied to.
In Common Building Block Keyboard Specification, all CBB compliant keyboards were to comply with the Windows Vista Hardware Start Button specification beginning in 2007-06-01.
Read more about this topic: Windows Key