Precision instrument runway markings.
There are three types of markings on civil airfields: visual, non-precision instrument, and precision instrument. Military airfields may use abbreviated markings in some cases. The basic markings on runways used for operations under VFR (visual flight rules) consist of centerline markings, runway direction numbers, and if required, letters. Threshold markings are also there, provided the runway is used, or intended to be used, by international commercial operators. In addition, aiming point markings are on runways 4,000 ft or longer or intended for use by jet aircraft. Non-Precision instrument runways have all the markings mentioned for visual runways. Precision instrument runways have in addition side-strip markings and a touchdown zone marking.