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