# Property talk:P4020

Active discussions

## Documentation

ISQ dimension
property of an observable physical quantity being a product of the SI base dimensions (length, mass, time, etc.)
Representsdimension of physical quantity (Q19110), International System of Quantities (Q16203461)
Has qualityobserver (Q28973077)
Data typeMathematical expression
Domain
According to this template: physical quantity (Q107715)
According to statements in the property:
individual quantity (Q71550118) or Wikidata property for physical quantities (Q21077852)
When possible, data should only be stored as statements
Allowed valuesL^aM^bT^cI^dΘ^eN^fJ^g (note: this should be moved to the property statements)
Exampletorque (Q48103)${\displaystyle {\mathsf {L}}^{2}{\mathsf {M}}{\mathsf {T}}^{-2}}$
entropy (Q45003)${\displaystyle {\mathsf {L}}^{2}{\mathsf {M}}{\mathsf {T}}^{-2}{\mathsf {\Theta }}^{-1}}$
Lists
Proposal discussionProposal discussion
Current uses
 Total 1,353 Main statement 1,351 99.9% of uses Qualifier 2 0.1% of uses
[create Create a translatable help page (preferably in English) for this property to be included here]
 Type “individual quantity (Q71550118), Wikidata property for physical quantities (Q21077852)”: element must contain property “instance of (P31)” with classes “individual quantity (Q71550118), Wikidata property for physical quantities (Q21077852)” or their subclasses (defined using subclass of (P279)). (Help)Exceptions are possible as rare values may exist. List of this constraint violations: Database reports/Constraint violations/P4020#type Q71550118, Q21077852, SPARQL, SPARQL (new)
 Scope is as main value (Q54828448): the property must be used by specified way only (Help) List of this constraint violations: Database reports/Constraint violations/P4020#scope, hourly updated report, SPARQL, SPARQL (new)
 Single value: this property generally contains a single value. (Help)Exceptions are possible as rare values may exist. List of this constraint violations: Database reports/Constraint violations/P4020#Single value, SPARQL, SPARQL (new)
 Allowed entity types are Wikibase item (Q29934200): the property may only be used on a certain entity type (Help)Exceptions are possible as rare values may exist. List of this constraint violations: Database reports/Constraint violations/P4020#allowed entity types, SPARQL (new)
 Please notify projects that use this property before big changes (renaming, deletion, merge with another property, etc.)

## Font style: should be Roman (upright), not italics

The font style should be Roman (upright), not italics. That is the seven symbols: LMTIΘNJ. For example torque (Q48103),

not ${\displaystyle {\displaystyle L^{2}MT^{-2}}}$
but ${\displaystyle {{\mathsf {L}}^{2}{\mathsf {M}}{\mathsf {T}}^{-2}}}$

The seven symbols are not those of a physical quantity (Q107715) (which generally are in italics), but of a dimension of physical quantity (Q19110). See also Wikidata:Property proposal/dimension. -DePiep (talk) 09:56, 11 January 2018 (UTC)

This a reference that supports DePiep's comment - in particular the dimension symbols specifically should be "symbolically represented by a single sans serif roman capital letter". Since this property has a "mathematical expression" value the default representation is in the italic form. I believe the underlying "mathematical expression" display just uses LaTeX (or the mediawiki version of it) to handle things, so do we want to replace these values with something that presents them consistently according to the BIPM recommendation in upright sans serif? I'm not even sure how you do that in LaTeX. ArthurPSmith (talk) 20:13, 18 January 2018 (UTC)
Ah - I fixed DePiep's example - the letters could be coded as {\mathsf X}. Do we want to apply this generally? ArthurPSmith (talk) 20:18, 18 January 2018 (UTC)
Why at all do you question my request while you yourself provided an extra source for it? What at all is wrong with this WD attitude? Really. I still have to meet a normal discussion here. -DePiep (talk) 01:09, 19 January 2018 (UTC)

The choice of LaTeX vs string data type seems to be inconsistent in general. With the same argument all quantity symbol (string) (P416) should use italic font. Apart from italic font I also do not know how to make subscripts for things like ${\displaystyle \varepsilon _{\mathrm {r} }}$  relative permittivity (Q4027242). I have seen some photometric quantities using [1] but can things like ${\displaystyle \varepsilon _{\mathrm {r} }}$  also be done with unicode letters? apparently yes: 𝜀ᵣ but depending on the font settings the result looks wrong. Also: Why apply mathsf to each letter seperately? I would simply write ${\displaystyle {\mathsf {L^{2}MT^{-2}}}}$ .Ok, I forgot that it also affects the exponents.--Debenben (talk) 15:18, 22 January 2018 (UTC)

• Why has this not been fixed? - DePiep (talk) 23:29, 1 April 2018 (UTC)
• @DePiep: and what is the proposed solution for that problem? Is it some changes in MediaWiki LaTeX extension, use \mathsf in this property in every case or switching this property datatype from mathematical expression to string? Wostr (talk) 00:43, 2 April 2018 (UTC)
@Wostr: Someone change the LaTeX code. In the OP here I did a demo, but I am not familiar enough with editing this in the property. - DePiep (talk) 09:56, 2 April 2018 (UTC)
Hmm, but the Artur's proposition to use \mathsf is that someone should manually change this property in every item and add \mathsf, am I right ArthurPSmith? Maybe it is possible to do it using a regexp and file a bot request for this? And of course use Wikidata usage instructions (P2559) in this property to indicate that \mathsf should be used in every case. Wostr (talk) 13:59, 2 April 2018 (UTC)

I fixed all values by using \mathsf. Toni 001 (talk) 14:08, 19 December 2019 (UTC)