Module:Val/units/doc

This is the documentation page for Module:Val/units

Val units are published at Template:Val/list, but here is where they are configured. Here you can easily add or remove a Val unit, or modify its link or markup, as seen at Val/list.

The common reference for a unit is the unit code, which equates to the markup and link of a unit.

Convert and Val share units in the following way. Val displays units of measurement, so Val could need any or all units. Some of the unit codes Val accepts are manage by {{Convert}}, but not all units of measurement are needed in conversions, so Val needs all of Convert's units and some of its own. Convert and Val unit codes are mostly identical.

Anyone can just add a unit here, and it will work for Val. You don't really need to know all the gory details. But here they are.

Given any unit, the only differences between Val and Convert could be that the unit code is different (rarely, such as for C and F).
Given any unit code, the difference between Val and Convert could be the actual unit reference, and then the unit code results in unwanted markup or linkage; the two templates could differ entirely for that unit code.
Both Convert and Val can alias there own unit codes, and Val can alias Convert's unit codes. An alias references a unit code, and so an alias can change the markup, the link, or both.
Here, for any given unit code, you can override Convert, alias that unit code from Convert, or alias one of Val's unit codes for your own markup for your own use anywhere on the wiki.
Although units used in articles have definite stylistic standards of markup and link, there are many more pages where the style is up to you. Here you could even alias a unit for your own use, for any special occasions you care to imagine, where instances of your unit code give your Val unit, say, color, size, orientation, or any other such markup available in the WP:HTML#formatting.
If your unit code is not listed at {{Val/list}}, you can check for it at Template:Convert#Units, or discuss adding it or changing it at {{Convert}} (talk). To edit Convert's units yourself, follow the instructions at Module:Convert/data. At Convert the procedure for defining a unit is much more involved than it is here, because there every unit defined must reference each associated unit and the conversion factor.

Units on this page may be entered under:

local builtin_units for normal units, or under
local builtin_units_long_scale for long scale units.

You can enter any units in the "Unsorted units" section if you are not sure.

Defining a unit

Before saving changes to this page, test how the changes made here effect other pages. That test is a Show preview that requires a fullpagename.

Previewing this page with Val/list is different from previewing it with other pages. Val/list is a transclusion of this page, so previewing Val/list previews this page and it previews the edit box of this page, showing all changes immediately on what only seems to be another page.

Previewing this module page on Val/list is pretty much a required step. Previewing this module page on other other pages is recommended because it can prove your changes' effects on Val itself. Just run a Show preview on the fullpagename that uses Val with your unit code. If it is in a sortable table, this is a plus.

To maintain Val units

Edit this page, Module:Val/units. See below for the format of entries.
While editing, Show preview of this page on Template:Val/list, and check the markup and link you added. An "invalid definition" message is automatically available.
Make any further changes to Val/units, and Show preview again.
Show preview on any other fullpagename with the Val call on it.
Save your changes to this page.

Before removing any Val unit codes, you can check to see how unit codes may or may not be in use on the wiki by employing {{Template usage}}. For example, to see about changing or removing unit code J.s, do a {{tlusage|val|J\.s|0}} → hastemplate:"val" insource:/\{\{ *[Vv]al *\|[^}]*J\.s/ prefix::. (Do a \quote of any non-alphanumeric.)

Testing a new unit

To test a newly added unit not used on any page, you will need to run the preview on a sandbox page you have already created. Here are all the test cases you can preview there before saving your changes here; they are the four |u= parameters:

{{Val|9|u =            }}
{{Val|9|ul =           }}
{{Val|9|u=foo|up =     }}
{{Val|9|u=foo|upl =    }}

and the sortable table:

{| class="wikitable sortable" summary="Sortable table to test Val sorting"
! Val number and unit
|-
| {{val|5|u=      }} 
|-
| {{val|3|u=      }} 
|-
| {{val|1|u=      }} 
|-
| {{val|2|u=      }} 
|-
| {{val|4|u=      }} 
|}

If your unit accepts an SI prefix you can test, say, k, m, and G, with your unit, and compare with e notations 1e3, 1e6, and 1e9 in the number. For example, Val sorts these two as equal: 1e3 m (standard e notation) and 1 km.

What to look for

The linked and non-linked markup should look exactly the same.
Navigate to the new link. It is safe: you can go back in your browser to here.
The two |up= versions should have no space in front of them.
For SI prefixes sorting 2e3 (or 2000) should be greater than k (kilo prefix).

Format of the config file

An entry defining a unit for Val is a single line starting with the unit code, followed by at least two spaces, and then a wikilink:

code [[pagename|symbol]]

The wikilink must supply the pagename and the unit symbol. (Unlike other wikilinks, this one accepts no templates at all, such as {{subsup}}.)

Also this line is a recognized entry format:

code symbol pagename

Both of these lines are equivalent and contain the same three elements (although note the difference in their order):

unit code: Unit abbreviation. Composite units have dimensions, and use a dot . to multiply or a slash / to divide and a -1 to divide (or greater) to divide powers.

unit pagename: Title (or section) of an article.

unit symbol: Standard abbreviation. The symbol is either a simple abbreviation or contains Wikipedia HTML formatting for superscript, or subscript, the multiplication dot, etc. (Templates cannot be applied here.) Always use abbreviation tags to indicate the full name of the unit. (The full name of the unit can also be hover-text via a redirect, but prefer the tag.)

You can add unit-code aliases for:

capitalization: unit codes are case sensitive
divisor units: the -2 version for inverse squared, etc., so we end up with both the slash a/b and inversion ab-1 forms. For example when adding a unit like m/s, add the m⋅s−1 version as well.
multiplier units: consider using the * version as well as the . version.

The entry is ignored if it lacks at least two adjacent space characters. The second format also takes tabs in the second delimiter in order to help with the greater need for alignment there.

Scale

A scale may be entered following the link. For example, the following defines a unit with code billion, symbol billion, link 1,000,000,000, and scale 1e9 (1×10⁹). The scale affects the hidden sort key included in the result: for example, {{val|2|u=billion}} would sort after {{val|98.7|e=3}}.

billion            billion          1,000,000,000          1e9

SI

A unit may be defined as "SI" which means that the unit code begins with an SI prefix which will be interpreted by {{convert}}. For example, the following defines an SI unit with code kV, base symbol V, and link Volt. The symbol V refers to the base unit with the SI prefix removed. A unit defined in this manner will have its sort key scaled by convert according to the SI prefix: for example, {{val|1|u=kV}} would sort after {{val|999|u=V}}. This is useful for units which are not defined in convert, or which are defined but where a link different from that specified in convert is wanted.

kV                 V                Volt                   SI

Other flags

Flag words can be entered after a tab character or two or more spaces:

ALIAS specifies that the unit's symbol is the code for a unit defined in {{convert}}}.
ANGLE identifies the unit as an "angle" so the unit is displayed after the number and uncertainty values; ANGLE also implies NOSPACE.
NOSPACE prevents the default insertion of a non-breaking space before the unit symbol.
SI specifies that the unit's symbol is for a base unit after removing the SI prefix in the unit code.

Examples

See Template:Val/list for examples.

Say you are adding c₀, the speed of light in a vacuum, for example. The following entry will define your unit code as c0, your unit symbol as ''c''0, and the unit's article as Speed of light#Numerical value, notation, and units.

c0 [[Speed of light#Numerical value, notation, and unit symbol|''c''0]]

or

c0 ''c''0 Speed of light#Numerical value, notation, and units

Then preview with Template:Val/list , check for an error message next to the new unit, and test the link you gave.

After that the page with the (saved) Val calls is used to test the linked and non-linked versions of the normal and the per units:

{{val|0.891|u=c0}} → 0.891 c₀
{{val|0.891|ul=c0}} → 0.891 c₀
{{val|0.891|up=c0}} → 0.891/c₀
{{val|0.891|upl=c0}} → 0.891/c₀

For an entire example:

Put this in a sandbox: {{val/sandboxlua|1.23|ul=wocky}} → 1.23 wocky
Edit Module:Val/units and insert a line like the following (do not save yet):
wocky wocky Jabberwocky
Under "Preview page with this module" enter Template:Val/list, and click Show preview. It shows all of Val/units in the Val/list format, as it will become when you save this page. Say there are no errors, the markup looks good, and the link navigates to the best explanation of the unit.
Then in the same way of previewing, put the fullpagename of the sandbox from step 1, and click Show preview. It shows the whole page including the val under test.
If wanted, click "Save page" to save the edit to Module:Val/units.

If you want a unit to add for practice, add one from List of common physics notations, or from SI units#Units and prefixes.

There are many examples of composite units that have their own page, so adding a unit code for one of those should link to its page.

For a new composite unit you should probably link the whole composition, not individual parts of it. At least link the largest portion which could have its own page.

The val user can compose a divisor unit on the fly from existing unit codes, and with individually linked numerator and denominator. For example:

{{val|99|ul=m|upl=d}} → 99 m/d

The val user can compose a multiplier unit on the fly by using the |end= parameter to prepend to the unit, and these can also be individually linked. For example (in geology) there is already 333 ¹⁴C yr BP to use with |end=:

{{val|333|ul=uBP|end= [[megaannum|Ma]]}} → 333 Ma ¹⁴C yr BP".

For example Val/units says

m.s-1 [[Metre per second|m⋅s−1]] linking to an article titled Metre per second, not

m.s-1 [[Metre|m]]⋅[[Second|s]]−1 which has separate links to already existing unit codes.

Alias a Convert unit

If you are here to change the link or markup of a unit, but it is not listed at Val/units, sometimes you can find the unit markup and link that you do want, already existing at Template:Convert#Units. In that case you can change the unit code to whatever you'd prefer, and it will achieve your goal. For example, if {{Val|1|C}} is going to Celsius instead of Colombs, you can define your own unit code, say "degC".

The following defines degC to refer to the unit known as °C in convert. There is no link because a link is defined at Convert.

degC               °C               ALIAS