First window

First window may refer to:

• first broadcast syndication rights for a work
• the post-grant review period for third-party challenge and opposition of a pending patent or trademark
• a wavelength band or transmission window in fibre-optic communications
• the initial 4-6 hour period of ischemic preconditioning, known as classical or early preconditioning, in which a coronary occlusion can limit injuries of a subsequent ischaemia reperfusion in the myocardium