Mathematica: The awesome Quantity system for values with units is everything the SysMLv1.x Quantity/Unit system should have been (and hopefully SysMLv2 will be)

In many English-speaking countries, however, the most common shape of a handwritten Arabic digit 1 is just a vertical stroke; that is, it lacks the upstroke added in many other cultures. Source Wikipedia

Webel vs SysPhS-1.1: Annex A.5: Humidifier: Where ValueTypes involving litre are defined, the Unit symbol "L" is used rather than the Modelica-preferred "l" (in combination with an explicit additional unit converter).

In 1990, the International Committee for Weights and Measures stated that it was too early to choose a single symbol for the litre. Source Wikipedia

In the UK and Ireland, as well as the rest of Europe, lowercase l is used with prefixes, though whole litres are often written in full (so, "750 ml" on a wine bottle, but often "1 litre" on a juice carton). Source Wikipedia

In these countries, the symbol L is also used with prefixes, as in mL and μL, instead of the traditional ml and μl used in Europe. Source Wikipedia

The United States National Institute of Standards and Technology now recommends the use of the uppercase letter L, a practice that is also widely followed in Canada and Australia. Source Wikipedia

Therefore, the digit "1" may easily be confused with the letter "l". In some computer typefaces, the two characters are barely distinguishable. As a result, L (uppercase letter L) was adopted by the CIPM as an alternative symbol for litre in 1979. Source Wikipedia

Originally, the only symbol for the litre was l (lowercase letter L), following the SI convention that only those unit symbols that abbreviate the name of a person start with a capital letter. Source Wikipedia

The litre (British English spelling) or liter (American English spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm^3), 1000 cubic centimetres (cm^3) or 0.001 cubic metre (m^3). Source Wikipedia

Webel vs SysPhS-1.1: Annex A.5: Humidifier: Where custom ValueTypes are defined, Modelica-friendly Unit symbols are used. Examples: "m3" not "m^3"; "degC" not "°C"; "J/(K.L)" (full stop as multiplier) not "J/(K⋅L)"; (EXCEPT "L" for litre not "l").

Webel vs SysPhS-1.1: Annex A.5: Humidifier: Dimensional analysis of VaporPressureCalculationConstraint implies each 1 mL of water is equated with EXACTLY 1 g of produced vapor.

QuantityKind and ValueType example - frequency vs clock frequency vs sound frequency This content has been marked as discussing an ADVANCED topic! Gallery Tutorial TRAIL: Webel's ultimate guide to Systems Modeling Language with MagicDraw/Cameo Section 08:03: The SysML QuantityKind and Unit Slide kind SysML Block Definition Diagram (BDD)

QuantityKind and ValueType example - length vs radius vs radius of tire This content has been marked as discussing an ADVANCED topic! Gallery Tutorial TRAIL: Webel's ultimate guide to Systems Modeling Language with MagicDraw/Cameo Section 08:03: The SysML QuantityKind and Unit Slide kind SysML Block Definition Diagram (BDD)

The only valid use of a Unit instance is to be referenced by the unit property of a ValueType stereotype. Source OMG Systems Modeling Language (SysML) 1.6

Two such InstanceSpecifications represent the same "measurement unit" if and only if their definitionURIs have values and their values are equal. Source OMG Systems Modeling Language (SysML) 1.6

The definitionURI of an InstanceSpecification classified by a kind of Unit identifies the particular "measurement unit" [VIM3-1.9] that the InstanceSpecification represents. Source OMG Systems Modeling Language (SysML) 1.6

Modelers specialize Unit as done in SysMLs QUDV model library or in a similar manner in other model libraries. Source OMG Systems Modeling Language (SysML) 1.6

Unit, or a specialization of it, classifies an InstanceSpecification to define a particular "measurement unit" in the sense of a "real scalar quantity, defined and adopted by convention, with which any other quantity of the same kind can be compared ... Source OMG Systems Modeling Language (SysML) 1.6

Unit is defined as a non-abstract SysML Block defined in the SysML UnitAndQuantityKind model library. Source OMG Systems Modeling Language (SysML) 1.6

A unit may also specify less stable or precise ways to express some value, such as a cost expressed in some currency, or a severity rating measured by a numerical scale. Source OMG Systems Modeling Language (SysML) 1.6

A unit often relies on precise and reproducible ways to measure the unit. For example, a unit of length such as meter may be specified as a multiple of a particular wavelength of light. Source OMG Systems Modeling Language (SysML) 1.6

A Unit is a quantity in terms of which the magnitudes of other quantities that have the same quantity kind can be stated. Source OMG Systems Modeling Language (SysML) 1.6

The only valid use of a QuantityKind instance is to be referenced by the quantityKind property of a ValueType or Unit. Source OMG Systems Modeling Language (SysML) 1.6

Two such InstanceSpecifications represent the same "kind-of-quantity" if and only if their definitionURIs have values and their values are equal. Source OMG Systems Modeling Language (SysML) 1.6

The definitionURI of an InstanceSpecification classified by a kind of QuantityKind identifies the particular "kind-of-quantity" [VIM3-1.2] that the InstanceSpecification represents. Source OMG Systems Modeling Language (SysML) 1.6

Modelers specialize QuantityKind as done in SysMLs QUDV model library or in a similar manner in other model libraries. Source OMG Systems Modeling Language (SysML) 1.6

... a SysML value property is understood to correspond to the VIM concept of "quantity" defined as a "property of a phenomenon, body or substance, where the property has a magnitude that can be expressed as a number and a reference" [VIM3-1.1]. Source OMG Systems Modeling Language (SysML) 1.6

QuantityKind, or a specialization of it, classifies an InstanceSpecification to define a particular "kind-of-quantity" in the sense of an "aspect common to mutually comparable quantities" [VIM3-1.2], ... Source OMG Systems Modeling Language (SysML) 1.6

QuantityKind is defined as a non-abstract SysML Block defined in the SysML UnitAndQuantityKind model library. Source OMG Systems Modeling Language (SysML) 1.6

A QuantityKind is a kind of quantity that may be stated by means of defined units. For example, the quantity kind of length may be measured by units of meters, kilometers, or feet. Source OMG Systems Modeling Language (SysML) 1.6

SysML ValueType and QUDV overview Gallery Tutorial TRAIL: Webel's ultimate guide to Systems Modeling Language with MagicDraw/Cameo Section 08:02: The SysML ValueType, Unit, and using values Slide kind SysML Block Definition Diagram (BDD)

QUDV in SysML refers to: Quantity, Unit, Dimension, Value. It is strongly influenced by the International Vocabulary of Metrology (VIM).