How many mL is in 300,000 units?

Answer 1

The si unit of volume is essentially Litre.

(you haven't specified which unit.)

1 L= 1000 ml

100,000 L= 100,000,000 mL

Answer 2

33 cm), just a few centimeters longer than the size of a foot.As in China and Korea, Japan employed different shaku for different purposes. The "carpentry" shaku (曲尺, kanejaku) was used for construction. It was a little longer in the 19th century prior to its metric redefinition. The "cloth" or "whale" shaku (鯨尺, kujirajaku), named for tailors' and fabric merchants' baleen rulers, was ​1⁄4 longer and used in measuring cloth. (A longer unit of about 25 cloth shaku was the tan.) Traditional Japanese clothing was reckoned using the "traditional clothing" shaku (呉服尺, gofukujaku), about ​1⁄5 longer than the carpentry shaku. The Shōsōin in Nara has ivory 1-shaku rulers, the kōgebachiru-no-shaku (紅牙撥鏤尺).The Japanese ri is now much longer than the Chinese or Korean li, comprising 36 chō, 2160 ken, or 12,960 shaku. A still longer unit was formerly standard in Ise on Honshu and throughout the 9 provinces of Kyushu, which comprised 50 chō, 3000 ken, or 18,000 shaku. The imperial nautical mile of 6080 feet (1853.19 m) was also formerly used by the Japanese in maritime contexts as a "marine ri". A fourth and shorter ri of about 600 m is still evident in some beach names. The "99-Ri" beach at Kujukuri is about 60 km. The "7-Ri" beach at Shichiri is 4.2 km long. The traditional units are still used for construction materials in Japan. For example, plywood is usually manufactured in 182 cm × 91 cm (about 72 in × 36 in) sheets known in the trade as saburokuhan (3 × 6版), or 3 × 6 shaku. Each sheet is about the size of one tatami mat. The thicknesses of the sheets, however, are usually measured in millimetres. The names of these units also live in the name of the bamboo flute shakuhachi (尺八), literally "shaku eight", which measures one shaku and eight sun, and the Japanese version of the Tom Thumb story, Issun Bōshi (一寸法師), literally "one sun boy", as well as in many Japanese proverbs. The base unit of Japanese area is the tsubo, equivalent to a square ken or 36 square shaku. It is twice the size of the jō, the area of the Nagoya tatami mat. Both units are used informally in discussing real estate floorspace. Due to historical connections, the tsubo is still used as the official base unit of area in Taiwan.In agricultural contexts, the tsubo is known as the bu. The larger units remain in common use by Japanese farmers when discussing the sizes of fields. The base unit of Japanese volume is the shō, although the gō now sees more use since it is reckoned as the appropriate size of a serving of rice or sake. Sake bottles are now marketed as containing 1800 mL exactly.The koku is historically important: since it was reckoned as the amount of rice necessary to feed a person for a single year, it was used to compute agricultural output and official salaries. The koku of rice was sometimes reckoned as 3000 "sacks". By the 1940s the shipping koku was ​1⁄10 of the shipping ton of 40 or 42 cu ft (i.e., 110–120 L); the koku of timber was about 10 cu ft (280 L); and the koku of fish, like many modern bushels, was no longer reckoned by volume but computed by weight (40 kan). The shakujime of timber was about 12 cu ft (340 L) and the taba about 108 ft³ (3,100 L or 3.1 m3). The base unit of Japanese mass is the kan, although the momme is more common. It is a recognised unit in the international pearl industry.The Japanese form of the Chinese tael was the ryō (両). It was customarily reckoned as around 4 or 10 momme but, because of its importance as a fundamental unit of the silver and gold bullion used as currency in medieval Japan, it varied over time and location from those notional values. Imperial units are sometimes used in Japan. Feet and inches are used for most non-sport bicycles, whose tyre sizes follow a British system; for sizes of magnetic tape and many pieces of computer hardware; for photograph sizes; and for the sizes of electronic displays for electronic devices. Photographic prints, however, are usually rounded to the nearest millimetre and screens are not described in terms of inches but "type" (型, gata). For instance, a television whose screen has a 17-inch diagonal is described as a "17-type" (17型) and one with a 32-inch widescreen screen is called a "32-vista-type" (32V型). A milliradian (SI-symbol mrad, sometimes also abbreviated mil) is an SI derived unit for angular measurement which is defined as a thousandth of a radian (0.001 radian). Milliradians are used in adjustment of firearm sights by adjusting the angle of the sight compared to the barrel (up, down, left, or right). Milliradians are also used for comparing shot groupings, or to compare the difficulty of hitting different sized shooting targets at different distances. When using a scope with both mrad adjustment and a reticle with mrad markings (called an "mrad/mrad scope"), the shooter can use the reticle as a 'ruler' to count the number of mrads a shot was off-target, which directly translates to the sight adjustment needed to hit the target with a follow up shot. Optics with mrad markings in the reticle can also be used to make a range estimation of a known size target, or vice versa, to determine a target size if the distance is known, a practice called "milling". Milliradians are generally used for very small angles, which allows for very accurate mathematical approximations to more easily calculate with direct proportions, back and forth between the angular separation observed in an optic, linear subtension on target, and range. In such applications it is useful to use a unit for target size that is a thousandth of the unit for range, for instance by using the metric units millimeters for target size and meters for range. This coincides with the definition of the milliradian where the arc length is defined as 1/1,000 of the radius. A common adjustment value in firearm sights is 1 cm at 100 meters which equals 10 mm/100 m = 1/10 mrad. The true definition of a milliradian is based on a unit circle with a radius of one and an arc divided into 1,000 mrad per radian, hence 2,000 π or approximately 6,283.185 milliradians in one turn, and rifle scope adjustments and reticles are calibrated to this definition. There are also other definitions used for land mapping and artillery which are rounded to more easily be divided into smaller parts for use with compasses, which are then often referred to as "mils", "lines", or similar. For instance there are artillery sights and compasses with 6,400 NATO mils, 6,000 Warsaw Pact mils or 6,300 Swedish "streck" per turn instead of 360° or 2π radians, achieving higher resolution than a 360° compass while also being easier to divide into parts than if true milliradians were used. The milliradian (approximately 6,283.185 in a circle) was first used in the mid-19th century by Charles-Marc Dapples (1837–1920), a Swiss engineer and professor at the University of Lausanne. Degrees and minutes were the usual units of angular measurement but others were being proposed, with "grads" (400 gradians in a circle) under various names having considerable popularity in much of northern Europe. However, Imperial Russia used a different approach, dividing a circle into equilateral triangles (60° per triangle, 6 triangles in a circle) and hence 600 units to a circle. Around the time of the start of World War I, France was experimenting with the use of millièmes or angular mils (6400 in a circle) for use with artillery sights instead of decigrades (4000 in a circle). The United Kingdom was also trialing them to replace degrees and minutes. They were adopted by France although decigrades also remained in use throughout World War I. Other nations also used decigrades. The United States, which copied many French artillery practices, adopted angular mils, later known as NATO mils. Before 2007 the Swedish defence forces used "streck" (6300 in a circle, streck meaning lines or marks) (together with degrees for some navigation) which is closer to the milliradian but then changed to NATO mils. After the Bolshevik Revolution and the adoption of the metric system of measurement (e.g. artillery replaced "units of base" with meters) the Red Army expanded the 600 unit circle into a 6000 mil circle. Hence the Russian mil has a somewhat different origin than those derived from French artillery practices. In the 1950s, NATO adopted metric units of measurement for land and general use. NATO mils, meters, and kilograms became standard, although degrees remained in use for naval and air purposes, reflecting civil practices. Use of the milliradian is practical because it is concerned with small angles, and when using radians the small angle approximation shows that the angle approximates to the sine of the angle, that is sin ⁡ θ ≃ θ {\displaystyle \sin \theta \simeq \theta } . This allows a user to dispense with trigonometry and use simple ratios to determine size and distance with high accuracy for rifle and short distance artillery calculations by using the handy property of subtension: One mrad approximately subtends one meter at a distance of one thousand meters. More in detail, because subtension ≃ arc length {\displaystyle {\text{subtension}}\simeq {\text{arc length}}} , instead of finding the angular distance denoted by θ (Greek letter theta) by using the tangent function θ trig = arctan ⁡ subtension range {\displaystyle \theta _{\text{trig}}=\arctan {\frac {\text{subtension}}{\text{range}}}} ,one can instead make a good approximation by using the definition of a radian and the simplified formula: θ rad ≃ subtension range {\displaystyle \theta _{\text{rad}}\simeq {\frac {\text{subtension}}{\text{range}}}} Since a radian is mathematically defined as the angle formed when the length of a circular arc equals the radius of the circle, a milliradian, is the angle formed when the length of a circular arc equals 1/1000 of the radius of the circle. Just like the radian, the milliradian is dimensionless, but unlike the radian where the same unit must be used for radius and arc length, the milliradian needs to have a ratio between the units where the subtension is a thousandth of the radius when using the simplified formula. The approximation error by using the simplified linear formula will increase as the angle increases. For example, a 3.3×10−7% (or 0.00000033%) error for an angle of 0.1 mrad, for instance by assuming 0.1 mrad equals 1 cm at 100 m 0.03% error for 30 mrad, i.e. assuming 30 mrad equals 30 m at 1000 m 2.9% error for 300 mrad, i.e. assuming 300 mrad equals 300 m at 1000 mThe approximation using mrad is more precise than using another common system where 1′ (minute of arc) is approximated as 1 inch at 100 yards, where comparably there is a: 4.5% error by assuming that an angle of 1′ equals 1 inch at 100 yd 55% error for 100′, i.e. assuming 100′ equals 100 in at 100 yd 953% error for 1000′, i.e. assuming 1000′ equals 1000 inches at 100 yd Milliradian adjustment is commonly used as a unit for clicks in the mechanical adjustment knobs (turrets) of iron and scope sights both in the military and civilian shooting sports. New shooters are often explained the principle of subtensions in order to understand that a milliradian is an angular measurement. Subtension is the physical amount of space covered by an angle and varies with distance. Thus, the subtension corresponding to a mrad (either in an mrad reticle or in mrad adjustments) varies with range. Knowing subtensions at different ranges can be useful for sighting in a firearm if there is no optic with an mrad reticle available, but involves mathematical calculations, and is therefore not used very much in practical applications. Subtensions always change with distance, but an mrad (as observed through an optic) is always an mrad regardless of distance. Therefore, ballistic tables and shot corrections are given in mrads, thereby avoiding the need for mathematical calculations. If a rifle scope has mrad markings in the reticle (or there is a spotting scope with an mrad reticle available), the reticle can be used to measure how many mrads to correct a shot even without knowing the shooting distance. For instance, assuming a precise shot fired by an experienced shooter missed the target by 0.8 mrad as seen through an optic, and the firearm sight has 0.1 mrad adjustments, the shooter must then dial 8 clicks on the scope to hit the same target under the same conditions. General purpose scopes Gradations (clicks) of 1/4′, 1/10 mrad and 1/2′ are used in general purpose sights for hunting, target and long range shooting at varied distances. The click values are fine enough to get dialed in for most target shooting and coarse enough to keep the number of clicks down when dialing. Speciality scopes 0.25/10 mrad, 1/8′ and 0.5/10 mrad are used in speciality scope sights for extreme precision at fixed target ranges such as benchrest shooting. Some specialty iron sights used in ISSF 10 m, 50 m and 300 meter rifle come with adjustments in either 0.5/10 mrad or 0.25/10 mrad. The small adjustment value means these sights can be adjusted in very small increments. These fine adjustments are however not very well suited for dialing between varied distances such as in field shooting because of the high number of clicks that will be required to move the line of sight, making it easier to lose track of the number of clicks than in scopes with larger click adjustments. For instance to move the line of sight 0.4 mrad, a 0.1 mrad scope must be adjusted 4 clicks, while comparably a 0.05 mrad and 0.025 mrad scope must be adjusted 8 and 16 clicks respectively. Others 1.5/10 mrad and 2/10 mrad can be found in some short range sights, mostly with capped turrets, but are not very widely used. Subtension refers to the length between two points on a target, and is usually given in either centimeters, millimeters or inches. Since an mrad is an angular measurement, the subtension covered by a given angle (angular distance or angular diameter) increases with viewing distance to the target. For instance the same angle of 0.1 mrad will subtend 10 mm at 100 meters, 20 mm at 200 meters, etc., or similarly 0.39 inches at 100 m, 0.78 inches at 200 m, etc. Subtensions in mrad based optics are particularly useful together with target sizes and shooting distances in metric units. The most common scope adjustment increment in mrad based rifle scopes is 0.1 mrad, which are sometimes called "one centimeter clicks" since 0.1 mrad equals exactly 1 cm at 100 meters, 2 cm at 200 meters, etc. Similarly, an adjustment click on a scope with 0.2 mrad adjustment will move the point of bullet impact 2 cm at 100 m and 4 cm at 200 m, etc. When using a scope with both mrad adjustment and a reticle with mrad markings (called a mrad/mrad scope), the shooter can spot his own bullet impact and easily correct the sight if needed. If the shot was a miss, the mrad reticle can simply be used as a "ruler" to count the number of mrads the shot was off target. The number of mrads to correct is then multiplied by ten if the scope has 0.1 mrad adjustments. If for instance the shot was 0.6 mrad to the right of the target, 6 clicks will be needed to adjust the sight. This way there is no need for math, conversions, knowledge of target size or distance. This is true for a first focal plane scope at all magnifications, but a variable second focal plane must be set to a given magnification (usually its maximum magnification) for any mrad scales to be correct. When using a scope with mrad adjustments, but without mrad markings in the reticle (i.e. a standard duplex cross-hair on a hunting or benchrest scope), sight correction for a known target subtension and known range can be calculated by the following formula, which utilizes the fact that an adjustment of 1 mrad changes the impact as many millimeters as there are meters: adjustment in mrad = subtension in mm range in m {\displaystyle {\text{adjustment in mrad}}={\frac {\text{subtension in mm}}{\text{range in m}}}} For instance: 20 mm/50 m = 0.4 mrad, or 4 clicks with a 1/10 mrad adjustment scope. 50 mm/1000 m = 0.05 mrad, or 1 click with a 0.05 mrad adjustment scope.In firearm optics, where 0.1 mrad per click is the most common mrad based adjustment value, another common rule of thumb is that: An adjustment of ​1⁄10 mrad changes the impact as many centimeters as there are hundreds of meters. I.e., 1 cm at 100 meters, 2.25 cm at 225 meters, 0.5 cm at 50 meters, etc., see the table below The horizontal and vertical adjustment range of a firearm sight is often advertised by the manufacturer using mrad's. For instance a rifle scope may be advertised as having a vertical adjustment range of 20 mrad, which means that by turning the turret the bullet impact can be moved a total of 20 meters at 1000 meters (or 2 m at 100 m, 4 m at 200 m, 6 m at 300 m etc.). The horizontal and vertical adjustment ranges can be different for a particular sight, for instance a scope may have 20 mrad vertical and 10 mrad horizontal adjustment. Elevation differ between models, but about 10–11 mrad are common in hunting scopes, while scopes made for long range shooting usually have an adjustment range of 20–30 mrad (70–100 moa).Sights can either be mounted in neutral or tilted mounts. In a neutral mount (also known as "flat base" or non-tilted mount) the sight will point reasonably parallel to the barrel, and be close to a zero at 100 meters (about 1 mrad low depending on rifle and caliber). After zeroing at 100 meters the sight will thereafter always have to be adjusted upwards to compensate for bullet drop at longer ranges, and therefore the adjustment below zero will never be used. This means that when using a neutral mount only about half of the scope's total elevation will be usable for shooting at longer ranges: usable elevation in neutral mount = scope's total elevation 2 {\displaystyle {\text{usable elevation in neutral mount}}={\frac {\text{scope's total elevation}}{2}}} In most regular sport and hunting rifles (except for in long range shooting), sights are usually mounted in neutral mounts. This is done because the optical quality of the scope is best in the middle of its adjustment range, and only being able to use half of the adjustment range to compensate for bullet drop is seldom a problem at short and medium range shooting. However, in long range shooting tilted scope mounts are common since it is very important to have enough vertical adjustment to compensate for the bullet drop at longer distances. For this purpose scope mounts are sold with varying degrees of tilt, but some common values are: 3 mrad, which equals 3 m at 1000 m (or 0.3 m at 100 m) 6 mrad, which equals 6 m at 1000 m (or 0.6 m at 100 m) 9 mrad, which equals 9 m at 1000 m (or 0.9 m at 100 m)With a tilted mount the maximum usable scope elevation can be found by: maximum elevation with tilted mount = scope's total elevation 2 + base tilt {\displaystyle {\text{maximum elevation with tilted mount}}={\frac {\text{scope's total elevation}}{2}}+{\text{base tilt}}} The adjustment range needed to shoot at a certain distance vary with firearm, caliber and load. For example, with a certain .308 load and firearm combination, the bullet may drop 13 mrad at 1000 meters (13 meters). To be able to reach out, one could either: Use a scope with 26 mrad of adjustment in a neutral mount, to get a usable adjustment of 26 mrad/2 = 13 mrad Use a scope with 14 mrad of adjustment and a 6 mrad tilted mount to achieve a maximum adjustment of 14 mrad/2 + 6 = 13 mrad A shot grouping is the spread of multiple shots on a target, taken in one shooting session. The group size on target in milliradians can be obtained by measuring the spread of the rounds on target in millimeters with a caliper and dividing by the shooting distance in meters. This way, using milliradians, one can easily compare shot groupings or target difficulties at different shooting distances. group size in mrad = group size in mm range in m {\displaystyle {\text{group size in mrad}}={\frac {\text{group size in mm}}{\text{range in m}}}} If the firearm is attached in a fixed mount and aimed at a target, the shot grouping measures the firearms mechanical precision and the uniformity of the ammunition. When the firearm also is held by a shooter, the shot grouping partly measures the precision of the firearm and ammunition, and partly the shooter's consistency and skill. Often the shooters' skill is the most important element towards achieving a tight shot grouping, especially when competitors are using the same match grade firearms and ammunition. Many telescopic sights used on rifles have reticles that are marked in mrad. This can either be accomplished with lines or dots, and the latter is generally called mil-dots. The mrad reticle serves two purposes, range estimation and trajectory correction. With a mrad reticle-equipped scope the distance to an object can be estimated with a fair degree of accuracy by a trained user by determining how many milliradians an object of known size subtends. Once the distance is known, the drop of the bullet at that range (see external ballistics), converted back into milliradians, can be used to adjust the aiming point. Generally mrad-reticle scopes have both horizontal and vertical crosshairs marked; the horizontal and vertical marks are used for range estimation and the vertical marks for bullet drop compensation. Trained users, however, can also use the horizontal dots to compensate for bullet drift due to wind. Milliradian-reticle-equipped scopes are well suited for long shots under uncertain conditions, such as those encountered by military and law enforcement snipers, varmint hunters and other field shooters. These riflemen must be able to aim at varying targets at unknown (sometimes long) distances, so accurate compensation for bullet drop is required. Angle can be used for either calculating target size or range if one of them are known. Where the range is known the angle will give the size, where the size is known then the range is given. When out in the field angle can be measured approximately by using calibrated optics or roughly using one's fingers and hands. With an outstretched arm one finger is approximately 30 mrad wide, a fist 150 mrad and a spread hand 300 mrad. Milliradian reticles often have dots or marks with a spacing of 1 mrad in between, but graduations can also be finer and coarser (i.e. 0.8 or 1.2 mrad). While a radian is defined as an angle on the unit circle where the arc and radius have equal length, a milliradian is defined as the angle where the arc length is one thousandth of the radius. Therefore, when using milliradians for range estimation, the unit used for target distance needs to be thousand times as large as the unit used for target size. Metric units are particularly useful in conjunction with a mrad reticle because the mental arithmetic is much simpler with decimal units, thereby requiring less mental calculation in the field. Using the range estimation formula with the units meters for range and millimeters for target size it is just a matter of moving decimals and do the division, without the need of multiplication with additional constants, thus producing fewer rounding errors. distance in meters = target in millimeters angle in mrad {\displaystyle {\text{distance in meters}}={\frac {\text{target in millimeters}}{\text{angle in mrad}}}} The same holds true for calculating target distance in kilometers using target size in meters. distance in kilometers = target in meters angle in mrad {\displaystyle {\text{distance in kilometers}}={\frac {\text{target in meters}}{\text{angle in mrad}}}} Also, in general the same unit can be used for subtension and range if multiplied with a factor of thousand, i.e. distance in meters = target in meters angle in mrad × 1 , 000 {\displaystyle {\text{distance in meters}}={\frac {\text{target in meters}}{\text{angle in mrad}}}\times 1,000} If using the imperial units yards for distance and inches for target size, one has to multiply by a factor of ​1000⁄36 ≈ 27.78, since there are 36 inches in one yard. distance in yards = target in inches angle in mrad × 27.78 {\displaystyle {\text{distance in yards}}={\frac {\text{target in inches}}{\text{angle in mrad}}}\times 27.78} If using the metric unit meters for distance and the imperial unit inches for target size, one has to multiply by a factor of 25.4, since one inch is defined as 25.4 millimeters. distance in meters = target in inches angle in mrad × 25.4 {\displaystyle {\text{distance in meters}}={\frac {\text{target in inches}}{\text{angle in mrad}}}\times 25.4} Land Rovers are about 3 to 4 m long, "smaller tank" or APC/MICV at about 6 m (e.g. T-34 or BMP) and about 10 m for a "big tank." From the front a Land Rover is about 1.5 m wide, most tanks around 3–3.5 m. So a SWB Land Rover from the side are one finger wide at about 100 m. A modern tank would have to be at a bit over 300 m. If for instance a target known to be 1.5 m in height (1500 mm) is measured to 2.8 mrad in the reticle, the range can be estimated to: distance in meters = 1500 mm 2.8 mrad = 535.7 m {\displaystyle {\text{distance in meters}}={\frac {1500{\text{ mm}}}{2.8{\text{ mrad}}}}=535.7{\text{ m}}} So if the above-mentioned 6 m long BMP (6000 mm) is viewed at 6 mrad its distance is 1000 m, and if the angle of view is twice as large (12 mrad) the distance is half as much, 500 m. When used with some riflescopes of variable objective magnification and fixed reticle magnification (where the reticle is in the second focal plane), the formula can be modified to: distance in meters = size in mm angle in mrad × mag 10 {\displaystyle {\text{distance in meters}}={\frac {\text{size in mm}}{\text{angle in mrad}}}\times {\frac {\text{mag}}{10}}} Where mag is scope magnification. However, a user should verify this with their individual scope since some are not calibrated at 10× . As above target distance and target size can be given in any two units of length with a ratio of 1000:1. It is possible to purchase rifle scopes with a mrad reticle and minute-of-arc turrets, but it is general consensus that such mixing should be avoided. It is preferred to either have both a mrad reticle and mrad adjustment (mrad/mrad), or a minute-of-arc reticle and minute-of-arc adjustment to utilize the strength of each system. Then the shooter can know exactly how many clicks to correct based on what he sees in the reticle. If using a mixed system scope that has a mrad reticle and arcminute adjustment, one way to make use of the reticle for shot corrections is to exploit that 14′ approximately equals 4 mrad, and thereby multiplying an observed corrections in mrad by a fraction of 14/4 when adjusting the turrets. In the table below conversions from mrad to metric values are exact (e.g. 0.1 mrad equals exactly 1 cm at 100 meters), while conversions of minutes of arc to both metric and imperial values are approximate. 0.1 mrad equals exactly 1 cm at 100 m 1 mrad ≈ 3.44′, so 1/10 mrad ≈ 1/3′ 1′ ≈ 0.291 mrad (or 2.91 cm at 100 m, approximately 3 cm at 100 m) Because of the definition of pi, in a circle with a diameter of one there are 2000 π milliradians (≈ 6283.185 mrad) per full turn. In other words, one real milliradian covers just under 1/6283 of the circumference of a circle, which is the definition used by telescopic rifle sight manufacturers in reticles for stadiametric rangefinding.For maps and artillery, three rounded definitions are used which are close to the real definition, but more easily can be divided into parts. The different map and artillery definitions are sometimes referred to as "angular mils", and are: 1/6400 of a circle in NATO countries. 1/6000 of a circle in the former Soviet Union and Finland (Finland phasing out the standard in favour of the NATO standard). 1/6300 of a circle in Sweden. The Swedish term for this is streck, literally "line".Reticles in some artillery sights are calibrated to the relevant artillery definition for that military, i.e. the Carl Zeiss OEM-2 artillery sight made in East Germany from 1969 to 1976 is calibrated for the eastern bloc 6000 mil circle.Various symbols have been used to represent angular mils for compass use: mil, MIL and similar abbreviations are often used by militaries in the English speaking part of the world. ‰, called "artillery per milles" (German: Artilleriepromille), a symbol used by the Swiss Army. ¯, called "artillery line" (German: artilleristische Strich), a symbol used by the German Army (not to be confused with Compass Point (German: Nautischer Strich, 32 "nautical lines" per circle) which sometimes use the same symbol. However, the DIN standard (DIN 1301 part 3) is to use ¯ for artillery lines, and " for nautical lines.) ₥, called "thousandths" (French: millièmes), a symbol used on some older French compasses. v (Finnish: piiru, Swedish: delstreck), a symbol used by the Finnish Defence Forces for the standard Warsaw Pact mil. Sometimes just marked as v if superscript is not available. Artillery uses angular measurement in gun laying, the azimuth between the gun and its target many kilometers away and the elevation angle of the barrel. This means that artillery uses mils to graduate indirect fire azimuth sights (called dial sights or panoramic telescopes), their associated instruments (directors or aiming circles), their elevation sights (clinometers or quadrants), together with their manual plotting devices, firing tables and fire control computers. Artillery spotters typically use their calibrated binoculars to move fired projectiles' impact onto a target. Here they know the approximate range to the target and so can read off the angle (+ quick calculation) to give the left/right corrections in meters. A mil is a meter at a range of one thousand meters (for example, to move the impact of an artillery round 100 meters by a gun firing from 3 km away, it is necessary to shift the direction by 100/3 = 33.3 mils.) The milliradian (and other SI multiples) is also used in other fields of science and technology for describing small angles, i.e. measuring alignment, collimation, and beam divergence in optics, and accelerometers and gyroscopes in inertial navigation systems. A fireteam or fire team is a small military sub-subunit of infantry designed to optimise "bounding overwatch" and "fire and movement" tactical doctrine in combat. Depending on mission requirements, a typical fireteam consists of four or fewer members: an automatic rifleman, a grenadier, a rifleman, and a designated team leader. The role of each fireteam leader is to ensure that the fireteam operates as a cohesive unit. Two or three fireteams are organised into a section or squad in co-ordinated operations, which is led by a squad leader. Historically, nations with effective fireteam organisation have had a significantly better performance from their infantry units in combat than those limited to operations by traditionally larger units. US Army doctrine recognizes the fire team, or crew, as the smallest military organization while NATO doctrine refers to this level of organization simply as team. Fireteams are the most basic organization upon which modern infantry units are built in the British Army, Royal Air Force Regiment, Royal Marines, United States Army, United States Marine Corps, United States Air Force Security Forces, Canadian Forces, and Australian Army. The concept of the fireteam is based on the need for tactical flexibility in infantry operations. A fireteam is capable of autonomous operations as part of a larger unit. Successful fireteam employment relies on quality small unit training for soldiers, experience of fireteam members operating together, sufficient communications infrastructure, and a quality non-commissioned officer corps to provide tactical leadership for the team. These requirements have led to successful use of the fireteam concept by more professional militaries. It is less useful for armies employing massed infantry formations, or with significant conscription. Conscription makes fireteam development difficult, as team members are more effective as they build experience over time working together and building personal bonds. In combat, while attacking or manoeuvring, a fireteam generally spreads over a distance of 50 metres (160 ft), while in defensive positions the team can cover up to the range of its weapons or the limits of visibility, whichever is less. In open terrain, up to 500 metres (1,600 ft) can be covered by an effective team, although detection range limits effectiveness beyond 100 metres (330 ft) or so without special equipment. A team is effective so long as its primary weapon remains operational. In the Canadian Army 'fireteam' refers to two soldiers paired for fire and movement. Two fireteams form an 'assault group' which is analogous to most other militaries' understanding of a fireteam; two assault groups and a vehicle group of one driver and one gunner form a section of ten soldiers. Team leader: The NCO (Sergeant if Assault Group 1, Master Corporal if Assault Group 2) carries a C7 rifle. Rifleman: One corporal or private carries a C7 rifle. Grenadier: One corporal or private carries a C7 rifle with an M203 grenade launcher. Gunner: One corporal or private carries a C9 light machine gun. The French section (groupe de combat – "combat group") is divided into two teams. The "fire team" (équipe de feu) is based around the section-level automatic rifle or light machine gun. The "shock team" (équipe de choc), made up of riflemen armed with rifle grenades or disposable rocket launchers, is the reconnaissance and maneuver unit. The teams employ bounding overwatch, with one element covering as the other moves. The team leaders have handheld radios so the elements can stay in contact with each other, as well as with the section leader's backpack radio set. The most common symbol of the modern French junior NCO (chef d'équipe) has been a radio hanging around their neck. Infantry units of the British Army, Royal Marines and RAF Regiment introduced the fireteam concept following the adoption of the SA80 rifle and light support weapon. An infantry section of eight men contains two fireteams, Charlie and Delta, each comprising an NCO (Corporal or Lance Corporal) and three privates. Team leader: The NCO carries an L85 rifle with an L123 underslung grenade launcher. Some units vary with one of the privates carrying the grenade launcher rather than the NCO. Rifleman: Two privates carry L85 rifles. Under earlier fireteam organisation there also were two riflemen, but the second of these was later substituted for a designated marksman, leaving the section with one rifleman per fireteam. From 2019, the earlier organisation was restored and the section commander was given discretion to re-role the section gunner as a third rifleman if needed. Gunner: One private per section carries an L7A2 GPMG. Earlier section organisations had one private per fireteam carrying an L86 light support weapon (intended to replace the L7A2) and then an L110 light machine gun; the L110A3 was removed from service in 2019, with the earlier L7A2 being reinstated as the section machine gun. Designated Marksman: One private per section carries an L129A1 sharpshooter rifle. Earlier fireteam organisations had one private per fireteam carrying either an L86A2 light support weapon or an L129A1 depending on availability; the L86A2 was removed from service in 2019, with the L129A1 officially becoming the standard section DMR.The fireteam is generally used as a subdivision of the section for fire and manoeuvre rather than as a separate unit in its own right, although fireteams or fireteam-sized units are often used for reconnaissance tasks, special operations, and urban patrols (usually being to referred to as a 'brick' in the latter scenario). Army The U.S. Army particularly emphasises the fireteam concept. Per U.S. Army doctrine a typical fire team consists of four soldiers. Team Leader (TL): Usually either a sergeant or corporal (although occasionally a team is led by a specialist or private first class when the platoon has a shortage of junior NCOs). Provides tactical leadership for the team at all times with a "Do As I Do" attitude; standard equipped with backpack GPS/radio set, and either an M16 rifle or M4 carbine. Rifleman (R): Is 'the baseline standard for all infantrymen'. They are equipped with the M16 rifle or M4 carbine. The rifleman is usually assigned with the grenadier to help balance the firepower capabilities of the automatic rifleman. Grenadier Rifleman (GR): Provides limited high-angle fire over 'Dead zones'. A grenadier is equipped with an M4/M16 with the M203 grenade launcher (or newer M320 grenade launcher) mounted to the weapon. Automatic Rifleman (AR): Provides overwatch and suppressive fire through force multiplication. The most casualty producing person in a fireteam, in terms of firepower and maneuverability when compared to the standard nine-man rifle squad. An automatic rifleman is equipped with a M249 light machine gun. The automatic rifleman is usually assigned with the team leader to maximize directed fields of fire and to help balance the firepower capabilities of the grenadier.In a Stryker Brigade Combat Team (SBCT)'s infantry rifle companies, one man in each rifle squad fireteam is either the squad anti-armour specialist (RMAT) armed with the FGM-148 Javelin, or the squad designated marksman (DM) who carries the M4 carbine and M14 rifle. In both cases, these two positions replace the basic rifleman of the standard rifle squad. Marine Corps The United States Marine Corps doctrine dictates that any active fireteam will include at least one 2-man gunnery-team and summarises its fireteam organisation with the mnemonic "ready-team-fire-assist", the following being the arrangement of the fireteam when in a column: Rifleman: acts as a scout for the fireteam; "Ready." Team Leader: uses the M203 and works as the designated grenadier; "Team." Designated Automatic Rifleman: uses the M249 light machine gun or M27 IAR and serves as second in command for the fireteam; "Fire." Assistant Automatic Rifleman: standard rifleman tasked with providing spotting support, range-finding, carries extra LMG-ammunition, and offering close-protection should the fireteam fall under attack; "Assist." Navy Navy Construction Force, "Seabee" Construction Battalions, utilise fireteams (as well as companies, platoons, and squads), similar in size to those employed by the USMC, in their organisational structure. Seabee units may be attached to Marine Corps units. Many other armed forces see the squad as the smallest military unit; some countries' armies have a pair consisting of two soldiers as the smallest military unit. In others a fireteam is composed of two pairs of soldiers (fire and manoeuvre team) forming a fireteam. Chinese military forces traditionally use a three-man 'cell' (equivalent to fireteam) as the smallest military formation. Fireteams have their origins in the early 20th century. From the Napoleonic Wars until World War I, military tactics involved central control of large numbers of soldiers in mass formation where small units were given little initiative. Groups of four soldiers were mainly employed for guard duty. In the Roman Army they were referred to as quaternio (Greek τετράδιον). Skirmishers in the Napoleonic War would often work in teams of two, ranging ahead of the main group and providing covering fire for each other. During World War I, trench warfare resulted in a stalemate on the Western Front. In order to combat this stalemate, the Germans developed a doctrinal innovation known as infiltration tactics (based on the Russian tactics used in the Brusilov Offensive), in which a brief intensive artillery preparation would be followed by small, autonomous teams of stormtroopers, who would covertly penetrate defensive lines. The Germans used their stormtroopers organised into squads at the lowest levels to provide a cohesive strike force in breaking through Allied lines. The British and Canadian troops on the Western Front started dividing platoons into sections after the Battle of the Somme in 1916. (This idea was later further developed in World War II). French Chasseur units in WWI were organised into fireteams, equipped with a light machine gun (Chauchat) team and grenades, to destroy German fire positions by fire (not assault) at up to 200 meters using rifle grenades. The light machine gun team would put suppressive fire on the enemy position, while the grenadier team moved to a position where the enemy embrasure could be attacked with grenades. The Chasseur tactics were proven during the Petain Offensive of 1917. Survivors of these French Chasseur units taught these tactics to American infantry, who used them with effectiveness at St. Mihiel and the Argonne. It was typical of a fireteam in this era to consist of four infantrymen: two assaulters with carbines, one grenadier, and one sapper. In the inter-war years, United States Marine Corps Captain Evans F. Carlson went to China in 1937 and observed Communist 8th Route Army units of the National Revolutionary Army in action against the Imperial Japanese Army. Carlson and Merritt A. Edson are believed to have developed the fireteam concept during the United States occupation of Nicaragua (1912–1933). At that time the US Marine squad consisted of a Corporal and seven Marines all armed with a bolt-action M1903 Springfield rifle and an automatic rifleman armed with a Browning Automatic Rifle. The introduction of the Thompson submachine gun and Winchester Model 1912 shotgun was popular with the Marines as a point-defense weapon for countering ambush by Nicaraguan guerrillas within the thick vegetation that could provide cover for a quick overrun of a patrol. A team of four men armed with these weapons had proven more effective in terms of firepower and manoeuvrability than the standard nine-man rifle squad. Carlson later brought these ideas back to the US when the country entered World War II. Under his command, the 2nd Marine Raider battalion were issued with the semi-automatic M1 Garand rifle and were organised in the standard 4-man fireteam (although it was called firegroup) concept, 3 firegroups to a squad with a squad leader. A firegroup was composed of an M1 Garand rifleman, a BAR gunner and a submachine gunner. After sustaining severe wounds, Carlson was replaced and his battalion later disbanded and re-organised under conventional Marine doctrine of ten-man squads. Later, Carlson's fireteam concept was re-adopted. WWII US Army rifle squads consisted of twelve soldiers divided into three teams: The A "Able" (contemporary spelling alphabet) team consisted of the squad leader and two scouts, the support B "Baker" team with the BAR gunner, assistant gunner, and ammunition bearer, and C "Charlie" team (assistant squad leader, also serving as the anti-tank grenadier, and five riflemen, one of whom served as the alternate anti-tank grenadier). In an assault the A team would provide overwatch and security or assist the C team in the assault, as the squad leader directed, while the B team provided suppressive fire. Suppressive fire from the BAR would be supplemented by fire from the rifles of his team as he reloaded, and could be further supplemented by platoon medium machine guns. The US Army Rangers and Special Service Force adopted an early Fire Team concept when on campaign in Italy and France. Each Squad sub-unit of 4 to 5 men was heavily armed. Each Fire Team was composed of a 2-man BAR automatic rifleman and assistant, a scout (marksman/grenadier) armed with a M1903 Springfield with a rifle grenade discharger, and a team leader armed with an M1 carbine or M1 SMG. Their later misuse as conventional infantry negated their special training and fighting skill and their use as "fire brigades" against larger enemy forces negated their advantages in aggressiveness and firepower. Meanwhile, the Communist Chinese established the three-man fireteam concept as the three-man cell when they organized a regular army, and its organization seemed to have been disseminated throughout all of Asia's communist forces, perhaps the most famous of which are the PAVN/NVA (People's Army of Vietnam/North Vietnamese Army) and the Viet Cong. A battle pair is the smallest unit above the individual soldier, in the modern era chiefly employed by Baltic militaries and special forces like the Special Air Service. It consists of two soldiers with one soldier acting as senior of the two fighters (decided amongst the two or by their superior). A fireteam in turn consists of at least two fire and manoeuvre teams, and a squad of two or more fireteams. It may be known in the US as a Fire and Manoeuvre team. The concept is not widely utilised. The United States and most Commonwealth armies rely on the concept of fire teams forming a squad. Such a team is known as a Lahingpaar or battle pair. Until 2015 in the Finnish Defence Forces, three taistelupari (combat pairs) formed a squad along with a squad leader. A three-man fireteam is now the smallest standard unit in the Finnish infantry doctrine. The French Army has the concept of a binôme ‘pair’. In the regular forces it is the pairing of an experienced soldier with a recruit or replacement. The new man learns from the experienced man how to properly perform the everyday tasks and responsibilities of his assignment. In the old Colonial Forces (like the French Foreign Legion) it was a means of imposing order. The pair were responsible for each other – if one member broke the rules or deserted, the other would be punished for not preventing it. According to the Swedish Armed Forces field manual, a Stridspar working in unison is as effective as four soldiers of same quality acting individually. The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total quantity of visible light emitted by a source per unit of time. Luminous flux differs from power (radiant flux) in that radiant flux includes all electromagnetic waves emitted, while luminous flux is weighted according to a model (a "luminosity function") of the human eye's sensitivity to various wavelengths. Lumens are related to lux in that one lux is one lumen per square metre. The 26th General Conference on Weights and Measures (CGPM) redefined the photometric units in 2018. With the new definition, which took effect on 20 May 2019, the lumen [...] is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 1012 Hz, Kcd, to be 683 when expressed in the unit lm W–1 [...] Prior to 2019, the definition was based on the candela. The lumen is related to the candela as 1 lm = 1 cd ⋅ sr.A full sphere has a solid angle of 4π steradians, so a light source that uniformly radiates one candela in all directions has a total luminous flux of 1 cd × 4π sr = 4π cd⋅sr ≈ 12.57 lumens. If a light source emits one candela of luminous intensity uniformly across a solid angle of one steradian, the total luminous flux emitted into that angle is one lumen (1 cd·1 sr = 1 lm). Alternatively, an isotropic one-candela light-source emits a total luminous flux of exactly 4π lumens. If the source were partly covered by an ideal absorbing hemisphere, that system would radiate half as much luminous flux—only 2π lumens. The luminous intensity would still be one candela in those directions that are not obscured. The lumen can be thought of casually as a measure of the total amount of visible light in some defined beam or angle, or emitted from some source. The number of candelas or lumens from a source also depends on its spectrum, via the nominal response of the human eye as represented in the luminosity function. The difference between the units lumen and lux is that the lux takes into account the area over which the luminous flux is spread. A flux of 1000 lumens, concentrated into an area of one square metre, lights up that square metre with an illuminance of 1000 lux. The same 1000 lumens, spread out over ten square metres, produces a dimmer illuminance of only 100 lux. Mathematically, 1 lx = 1