Vertical bar in the context of Palatal click

The lateral clicks are a family of click consonants found only in African languages. The clicking sound used by equestrians to urge on their horses is a lateral click, although it is not a speech sound in that context. Lateral clicks are found throughout southern Africa, for example in Zulu, and in some languages in Tanzania and Namibia. The place of articulation is not known to be contrastive in any language, and typically varies from alveolar to palatal.

The symbol in the International Phonetic Alphabet that represents a generic lateral click is ⟨ǁ⟩, a double vertical bar. Prior to 1989, ⟨ʖ⟩ was the IPA letter for the lateral clicks, and this is still preferred by some phoneticians, as the vertical bar may be confounded with prosody marks, two dental clicks, and in some fonts, with a double lowercase L. Either letter may be combined with a second letter to indicate the manner of articulation, though this is commonly omitted for tenuis clicks with a velar rear articulation.

A reticle or reticule, also known as a graticule or crosshair, is a pattern of fine lines or markings built into the eyepiece of an optical device such as a telescopic sight, spotting scope, theodolite, optical microscope or the screen of an oscilloscope, to provide measurement references during visual inspections. Today, engraved lines or embedded fibers may be replaced by a digital image superimposed on a screen or eyepiece. Both terms may be used to describe any set of patterns used for aiding visual measurements and calibrations, but in modern use reticle is most commonly used for weapon sights, while graticule is more widely used for non-weapon measuring instruments such as oscilloscope display, astronomic telescopes, microscopes and slides, surveying instruments and other similar devices.

There are many variations of reticle pattern; this article concerns itself mainly with the most rudimentary reticle: the crosshair. Crosshairs are typically represented as a pair of perpendicularly intersecting lines in the shape of a cross, "+", though many variations of additional features exist including dots, posts, concentric circles/horseshoes, chevrons, graduated markings, or a combination of above. Most commonly associated with telescopic sights for aiming firearms, crosshairs are also common in optical instruments used for astronomy and surveying, and are also popular in graphical user interfaces as a precision pointer. The reticle is said to have been invented by Robert Hooke, and dates to the 17th century. Another candidate as inventor is the amateur astronomer William Gascoigne, who predated Hooke.