Template:Val/doc

This template is used to easily present values in scientific notation, including uncertainty and/or units, as prescribed by Wikipedia's Manual of Style.

Introduction

Val stands for "value" and is used for numeric values in the various scientific notations, and also used for measurement values with physical units. It formats these according to the Manual of Style and keeps them from wrapping across lines.

Express a numeral, with various notations for uncertainty:

• {{val|123456.78901}} → value, formated with gaps: 123456.78901, or with |fmt=commas → 1,234.5678901.
• {{val|number|number}} → value ± uncertainty, like 123,478±56
• {{val|number|(number)}} → value(uncertainty), like 12,345(56).
• {{val|number|number|number}} →value ^+uncertainty
  _{−uncertainty} like 1234+56
  −78

Express values with units, for example kilograms {{val|4|u=kg}} → 4 kg. The letters kg are a "unit code" that |u= understands, and that |ul= links to Kilogram. Because the unit spacing and markup is a style issue, Val provides these for you. There are a large number of unit codes that Val understands and keeps "up to code". A unit code is usually composed of one or more abbreviated unit names and the usual math symbols on the typical keyboard. See {{Val/units}}.

Some unit-code flexibility is provided by having four parameters to work the unit-code system: whether to link one or not, and whether to form ad hoc ratios of any two unit codes:

• {{val|number|u=unit code}} → number markup , such as 9.8 m/s²
• {{val|number|ul=unit code}} → number [[Article|markup]], such as 9.8 m/s²
• {{val|number|u=unit code|upl=unit code}} → number markup/[[Article|markup]], such as 9.8 m/s²
• {{val|number|ul=unit code|up=unit code}} → [[Article|markup]]/markup, such as 9.8 m/s²

To bypass the unit code system, if |u= does not recognize your unit code, it will accept any wikitext and render it as usual.

• {{val|5.4|u=[[kg]]&sdot;[[meter|m]]/s<sup>2</sup>}} → 5.4 kg⋅m/s²
• {{val|7.6|u=[[metre per second squared|m/s<sup>2</sup>]]}} → 7.6 m/s²

Use ⋅ to multiply units. But see below for § How to add units how to add a unit code to Val yourself.

There are some things a unit code cannot do. So you can also prefix or suffix the call to Val with ad hoc wikitext using one or both of |p= and |s=:

• {{val|7600|p=>|s=<|u=C&sdot;Ga}} → >7600 C⋅Ga<
• {{val|7600|p=<span style="color:green"><sup>|s=</span></sup>|u=C}} → ^7600 C

See {{val/testcases}} to learn the val parameters by a example. It's comprehensive, and there's over 100 examples.

Arguments

1st	The numeric portion of the value. Defaults to 100. Accepts numbers that start with "." or "-" or "+".
2nd	The uncertainty in ± format. Wrap the number in parentheses for that format of uncertainty
3rd	The uncertainty in Template:Subsup format.
|e=	The exponent for a power of 10, spaced:×10e .
|fmt=	Format strings of more-than-four digits. Accepts commas. Defaults to slight gaps. Unlike gaps, "commas" has no effect on the decimal portion. {{val|-1234}} → −1234, {{val|1234|fmt=commas}} → 1,234.
|u= or |ul=	The unit code. Val adds a non-breaking space and the unit. Use |ul= to link the unit, but use |u= in consideration of WP:overlinking. In lieu of a unit code, |u= accepts and renders all wikitext.
|up= or |upl=	A "per" (or denominator) unit code. Instead of space Val adds the "per" slash. Commonly used in concert with another unit code in |u= or |ul= to form a ratio of unit codes. {{Val|120|p=$|upl=acre}} →$120/acre
|p=	A non-spaced prefix for value, such as ∆ or ⌀. Accepts wikitext (markup code). (The non-breaking space is  .)
|s=	A non-spaced suffix for value. Accepts wikitext (markup code). (The non-breaking space is  .)
|end=	Appends something after the main value. {{val|1234|end=^}} gives 123.24^
|errend=	Appends something after an uncertainty. {{val|1234|5678|errend=∞}} gives 1234±5678∞
|+errend= or |-errend=	Appends something after an uncertainty. {{val|123|4|5|+errend=H|-errend=L}} gives 1+2H −3L
|sortval=	Alternative sorting factor to 1
|us= or |ups=	Alternative unit code for sorting.
|long scale=	Usually a unit is the short ton and billion means 1×109. But there are long versions of these units and others. Use |long scale=on to assign your unit to the long scale instead. The unit code's link will change and it will sort differently in tables. "See Long and short scales".
|nocategory=	If set to any value, errors in the use of this template will not cause the page to be added to the Pages with incorrect formatting templates use category. This is useful for documentation and test pages that do not need to be fixed.

Errors

There is strict checking on the validity of arguments; any incorrect use will result in an error, which is displayed using {{FormattingError}}. Pages that contain incorrect use of this template will show up on Category:Pages with incorrect formatting templates use.

Format of numbers

{{Val}} produces formatting compliant with Wikipedia's Manual of Style.

The MOS recommends that numbers either be delimited using thin spaces either side of the decimal, or commas to the left and no delimiters to the right. Articles should be consistent with respect to the style of delimiting. The template defaults to the former style, this can be adjusted using |fmt= (see above).

Sorting

A hidden sort key is added to the output for sorting in sortable tables. The sort key is based on the main value (parameter |1=) and, if used, the exponent for the power of 10 (parameter |e=) and/or units (parameters |u=, |ul=, |up= and/or |upl=). Where necessary, units are converted to base SI units for the purpose of the sort key, which is produced by {{ntsh}}. Several units are covered; see § How to add units for those which are not. To omit the sort key use |sortable=off.

Examples

{{val|1234567890}}	→	1234567890
{{val|1.23456789}}	→	1.23456789
{{val|1.2345678}}	→	1.2345678
Template:Xpdop3c
Uncertainty/significance
{{val|1.234|0.005}}	→	1.234±0.005
{{val|1.234|+0.005|-0.006}}	→	1.234+0.005 −0.006
{{val|1.234|(5)}}	→	1.234(5)
Units
{{val|1.234|u=m}}	→	1.234 m
{{val|1.234|u=m2}}	→	1.234 m2
{{val|1.234|ul=m}}	→	1.234 m
{{val|123.4|ul=USgal}}	→	123.4 US gal
{{val|12.34|ul=mpgimp}}	→	12.34 mpg‑imp
{{val|12.34|u=deg}}	→	12.34°
{{val|1.234|0.005|u='}}	→	1.234′±0.005′
{{val|1.234|+0.005|-0.006|u="}}	→	1.234″+0.005″ −0.006″
Exponents
{{val|1.234|e=5|ul=m}}	→	1.234×105 m
{{val|1.234|0.056|e=7}}	→	(1.234±0.056)×107
{{val|1.23456|+0.00007|-0.00008|e=-9|ul=m/s}}	→	1.23456+0.00007 −0.00008×10−9 m/s
{{val|1.234|0.056|e=7|ul=psi}}	→	(1.234±0.056)×107 psi
{{val|1.234|(5)|e=-2}}	→	1.234(5)×10−2
Prefix/suffix
{{val|p=Δ |12.34}}	→	Δ 12.34
{{val|p=+|12.34|u=%}}	→	+12.34%
{{val|12.34|0.25|s=%}}	→	12.34±0.25%
Numerator/Denominator
{{val|1.234|e=7|ul=W|up=m2}}	→	1.234×107 W/m2

More examples
See the testcases at {{val/testcases}}.

Performance impact

For most uses, in the text of articles, Template:Val will not restrict performance, but when used inside the wikitext markup of large templates, there are some restrictions. When displaying integer amounts, Template:Val has an internal expansion depth of 15 levels, but for numbers with decimal portions, it uses 22 levels, or more.

How to add units

Add the unit to Template:Val/units. Val defaults to looking up units at {{Convert}}, but units added here override that.

Note these points about composite units before adding units:

• For composite units you should probably link the whole, not individual units. For example the line you add would say |m.s-1=[[Metre per second|m⋅s{{sup|−1}}]] linking to Metre per second, not |m.s-1=[[Metre|m]]⋅[[Second|s]]{{sup|−1}}. List of common physics notations has many examples of composite units that have their own page.
• The val user can compose their own divisor unit from an existing unit, for example writing {{val|99|ul=m|upl=s}} to render their own "99 m/s" with two links: m to Meter and s to Second.
• The val user can compose their own multiplier units by using the end parameter to prepend a string. For example, in a geology article, to prepend "Ma", to the unit in 333 ¹⁴C yr BP they could write {{val|333|end= Ma|ul=uBP}}, rendering "333 Ma ¹⁴C yr BP". (The end parameters cannot be linked.)

After adding a unit, you can ensure that it sorts correctly in a table, especially if there are ten or twenty variations that differ only by an SI prefix. (See § Sorting above and Template:Val/sortkey/unit.)

FAQ and comments

• Q: Why should I use Val?

A1: Val formats numbers:

• inserts spaces between groups of digits, approximating SI standards
• properly formats uncertainties in measurements and significant digits, providing a ± character, etc.
• properly formats exponents of 10 and scientific notation
• replaces "-" (hyphen) with a "−" (minus sign)

A2: Val preserves spacing:

• It makes sure the value does not wrap at the end of a line, so that it can always be read as a single value on one line in the text.
• It spaces the various parts of the value where they should be

A3: Configuring Val gives you your own code for automating the markup for, and a link to, any units in the entire Encyclopedia.

A4: Val helps make Wikipedia more consistent. It adheres to the Wikipedia Manual of Style for numbers. Updates to the MoS can be applied to this template, and result in automatic modification on values that use it. All this makes sure all values on all pages have the same look and feel because they will all use the same spacing, font size, positioning, etc, and makes updating and checking by the bots easier because they can recognize a value for what it is.

• Q: Why not use <math>?

A: For the same reasons HTML might be preferred over TeX:

• Because the font in math tags differs both in face and size from the prose, which can disturb the layout of a page when used inline with the prose.
• You cannot cut and paste a bitmap image rendered by the Latex.
• Images are slower to load and use more bandwidth, which is especially bad for the mobile version of Wikipedia.
• <math> does not automatically easily align to the Manual of Style for numbers.

• Q: Are there any known issues with Val?

A1: This template has been in full use on many pages for quite some time without major problems or breaking changes. Technically, there is no good reason not to try Val.

A2: Issues are solved rapidly by an active set of responsive template coders. See the talk page.

• Q: How should I use Val?

A1: Val probably already has your unit on its current list. If not, then your unit can be added.

A2: To avoid over linking switch from |ul= to |u= and from |upl= to |up=.

A3: Use Val along with {{Convert}}. See how to add units to Convert.

See also

• {{Val}} subtemplates:

  {{Val/units}}, for the list of customized units, their markup, their link, and to configure your own codename for your own unit (whose name you choose goes into any of the named parameters with the letter u in there names).

  Similarly {{Val/angle}}, for the handling of unspaced units.

  {{val/delimitnum}}, for setting your own delimiters between groups of digits instead of using the default (spaces).

  {{Val/sortkey/unit}} for guaranteeing table sorting

• {{formatting error}}, to fix inconsistencies when the error you are given is not the error you find you have.