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what about the byte like gigabyte and megabyte —Preceding unsigned comment added by 76.167.223.99 ( talk) 06:13, 29 September 2008 (UTC)
Hmmm. Are I'm infringing ones copyright by taking commonly used definitions??? Tobias Hoevekamp
Ah, here we go, perhaps Lee Daniel Crocker's comments in United States/President might reassure you. If not, perhaps this is a question for talk:Copyright?
-- dja
Yes, I don't see anything copyrightable here. Even if you took whole sentences out of the ISO specs, they're not copyrighted either--deliberately. That's the whole purpose of the ISO. --LDC
(Internation Standards (published by ISO) are copyright, the copyright is owned by ISO, they reserve all rights. There is no right to copy anything from an International Standard. Obviously this is often a problem if you want to implement, use, or descrribe one. Providing copyright free specifications is not the purpose of ISO. Alas. -- drj).
Are you sure that ISO waives their rights? ISO charges big bucks for most standards as a way to finance themselves. If these were really public domain, we would have seen a lot of them printed cheaply, or floating around the net, no? -- Robbe
Yes, some (OK, most) ISO specs are copyrighted--especially industrial standards. But they do grant explicit rights to the metric weights and measures stuff. I'll see if I can dig up a citation somewhere. --LDC
Woulnd't it be better to try to make this chart more free form, using indentation to get pre formatting, as with periodic table, so that it is easier to edit?
Although they are derived units, there are standard base units for derived quantities such as area (the are, as in "hectare") and the liter, these should be included, just as have been units like webers etc.
I'd do it, but frankly, I'm a bit put off by the table markup. Maybe I'll make an alternative table to demonstrate how I think it should be done.
And no, I don't think it's a violation of the copyright to transcribe facts, so long as you don't make an exact copy of the layout from the original. I saw someone address this issue recently in another context, I'll see if I can dig up the discussion and then post a link to it here.
-- dja
Something like this: SI derived units freeform table
I started by reading the HTML-formatted table with the character-based web browser "links" in a sufficiently wide terminal window, saving the formatted output to a file. I then passed it through the following perl one-liner to preserve the free formatted links, and to restore the superscripting:
perl -ne 's/|/ /g; s/[(S+s*S*s*S*)]?/ $1/g; s/(S+)?/ $1/g; s/(w)(-*d+)/$1$2/g; print' si_derived_units.txt > si_derived_units5.txt
Finally, I did some manual cleaning up in a text editor before copying and posting it.
FWIW, YMMV, and all that.
-- dja
Neither SI derived units freeform table nor SI derived unit look good to me. What I don't like is, that we are restricted to very basic mathematical formulations... -- th
Do you have an example of what would be more appropriate? Seems to me that one is going to run into such limitations with any tabular format. The freeform table is not intended so much for its prettiness (although I don't think it is downright *ugly* even so), but rather to make the layout more accessible and editable by people who are more interested in the content than in the minutiae of HTML markup. Such concern is fairly central to Wikis, in general.
-- dja
Problems with the freeform table: (a) It is difficult to get the alignment right, because the link brackets (4 chars) can turn into zero, one (the question mark), or three chars (? plus brackets). If somebody creates one of the dangling links on your page, the alignment changes and must be fixed. (b) Browsers may word-wrap PRE content, which makes the table almost unreadable. Mozilla does this. (c) SUP is not allowed inside PRE, and therefore most of the units are broken (m^2, m^-1, etc.). -- Robbe
(a) Granted, though perfect alignment isn't always necessary (b) OK (c) I see that this is so from
http://www.w3.org/TR/html4/sgml/dtd.html#pre.exclusion
Good thing I didn't change the main page too early. :-)
-- dja
what is a liter?
As_I_Understand_It, degree Celsius is NOT an SI unit, the Kelvin is. Anyone know how to confirm / refute this? SGBailey 10:34 Dec 12, 2002 (UTC)
The table suggests the "Celsius" is an unofficial unit of temperature. Shouldn't that be the "degree Celsius"? — Preceding unsigned comment added by 142.30.227.14 ( talk • contribs) 00:03, 29 April 2010 (UTC)
I dont see the dyne (symbol: dyn) mentioned here or on the force page. It appears to have a defined relationship with the newton. Is it a bastard unit of measure?
I have started changing some of the math formulas to use <math> constructs. I think this looks much better, and is not much more difficult to edit (see Wikipedia:TeX markup). If nobody objects, I will finish this off sometime soon. I agree that the freeform table looks pretty bad, and the html table isn't much better. I don't think the html table is too difficult to edit, but maybe I will format it in a way that makes it easier for people to understand how to edit. Or maybe I'll make my own attempt at a freeform table. We'll see... -- HN 21 May 2003
There are templates available e.g. [[Template:SI_derived_units]] and [[Template:SI_accepted_units]] which could be used to start this article. Would they be useful in this article? Ian Cairns 00:31, 8 Nov 2004 (UTC)
I propose that this be merged to Degree Celsius#Conversions. Jimp 14Oct05
It's already there, yes, but not in as concise a form. If we don't remove it from here it still may be worth duplicating it over there. You have a point, Gene, "this is a conversion within the International System of Units" however I wonder whether this is enough to warrant keeping the section here. The conversion is also covered in the SI derived units with special names table (as a mathematical formula). Is this not enough? There are a great number of things that might be called "quite relevant to the structure and usage of SI" (many of which may have just as good a reason to be included here) do we have room for them all? I say keep the details of particular units on their own pages, kelivins to Celcius being no exception. Jimp 21Oct05
Is there a reason why the SI base unit page says "...the fraction 1⁄273.16 (exactly)..." while the SI derived unit page says "t°C = tK − 273.15". I realize that 0.01 is a small amount, but they can't both be correct. TheAmigo42 ( talk) 22:06, 27 February 2008 (UTC)
All this chatter is irrelevant, as the Kelvin should not even appear in this list, as it is one of the seven basic SI units, NOT a "derived unit". Dumbhick ( talk) 13:09, 17 July 2008 (UTC)
Shouldn't the "Expression in terms of SI base units" be cd ^ -1 as it is 1/cd? -- I hate to register 12:43, 31 July 2006 (UTC)
Would it not be better and clearer to quote the Newton as being kg.m/s^2 rather than m.kg/s^2? After all Force is usually quoted as F=ma (mass x acceleration). Similar with Pascals. —Preceding unsigned comment added by 195.195.173.31 ( talk) 15:05, 6 November 2007 (UTC)
212.137.63.86 ( talk) 11:19, 6 August 2008 (UTC)
Correct me if I'm wrong, but I do not believe that E should be here. It's the symbol for the electromagnetic field, but not a unit of magnitude. It's comparable to T(time) and L(length) as opposed to being comparable to s(second) or kg(kilogram). I will go ahead and remove it on the grounds that it doesn't belong here. Feel free to revert back if I am wrong. I am a student and not a scientist. - 70.119.126.195 ( talk) 04:44, 22 November 2008 (UTC)
Specific Energy Density is the product of the specific energy of a material times its energy density. The higher the number, the more potential energy is contained in that substance. As the typical units of Specific Energy are m2/s2 or J/kg, and of Energy Density are kg/m·s2 or J/m3, so the product is equivalent to kg·m/s4 or J·J/kg·m3. Unfortunately there is no SI unit for this, but it is the best way of classifying a material by its energy content, since lower mass or less volume will increase the overall number. It's a pity there's no SI derived unit for this concept. May I name it? Surely I'm not the first to discuss it? But can we call it Jacobs? :)
-- TimeHorse ( talk) 19:18, 4 January 2011 (UTC)
I suggest adding 7 columns to the table: m, kg, s, A, K, Cd and mol, the values in each of these columns will be the exponent of the SI unit or 0 if that unit does not form part of the definition. For instance, Hertz would be 0, 0, -1, 0, 0, 0, 0; Newtons would be 1, 1, -2, 0, 0, 0, 0; Lumen would be 0, 0, 0, 0, 0, 1, 0; Volt would be 2, 1, -3, -1, 0, 0, 0; etc.
-- TimeHorse ( talk) 19:24, 4 January 2011 (UTC)
I propose to swap the order of the tables (to match the SI Brocure), so that Table 1 gives examples of the unlimited number of derived units and Table 2 is a list of specially-named derived units (so that the article discusses the general before the particular) Adamtester ( talk) 00:38, 14 January 2011 (UTC)
radians somehow cannot be expressed wouldn't that make it a base unit? —Preceding unsigned comment added by 79.71.100.247 ( talk) 22:56, 2 April 2011 (UTC)
The table stated incorrectly that 1 °C = 1 K - 273.15. What is meant is that 1 °C = 1 K, but that the degree Celsius is used for reporting temperatures relative to 273.15 K. Dondervogel 2 ( talk) 07:31, 5 January 2015 (UTC)
@ User:Dondervogel 2 1 °C = 1 K - 273.15 it is obvious. but 1 °C = 1 K is definitely wrong! °C can never be equal to K.
Δ°C= ΔK
~" aGastya" ✉ let’s talk about it :) 14:50, 18 February 2015 (UTC) Dondervogel 2 ( talk) 15:29, 18 February 2015 (UTC) I think what you mean is that the numerical value of temperature expressed in deg Celsius is never equal to the numerical value of temperature expressed in kelvin. I agree with this statement, but it is not what I said. What I said, in equation form, (and meant) is that the unit degree Celcius is identical the unit kelvin. Dondervogel 2 ( talk) 15:29, 18 February 2015 (UTC)
Yeah, they just depend in +273.15 but deg C isn't SI unit
~"
aGastya"
✉ let’s talk about it :)
11:22, 19 February 2015 (UTC)
N-m is for Torque as well as Energy too. Should not that too be added in the table? thanks! ~" aGastya" ✉ let’s talk about it :) 11:50, 18 February 2015 (UTC)
second inverse is there in table of "Named units derived from SI base units" metre inverse is names in table of "Some SI derived units" Why so? both of them should be in a same table, isn't it? And then also "Angular Frequency" is also missing in the table (second inverse) Thanks ~" aGastya" ✉ let’s talk about it :) 11:58, 18 February 2015 (UTC)
According to [ [2]], nautical miles (and by extension, knots) are acceptable non-SI units. Why aren't they on the page or the template? Is this an example of systemic bias against imperial units? — Preceding unsigned comment added by 161.149.102.86 ( talk) 06:20, 8 July 2016 (UTC)
The 'expression in terms of SI base units' for lumen per watt 'm−2⋅kg−1⋅s3⋅lm' should be changed into 'm−2⋅kg−1⋅s3⋅cd' in order to be consistent with the SI base unit table. — Preceding unsigned comment added by 176.127.191.90 ( talk) 08:47, 10 September 2016 (UTC)
An editor has asked for a discussion to address the redirect Planck electric potential. Please participate in the redirect discussion if you wish to do so. signed, Rosguill talk 17:36, 8 April 2020 (UTC)
Why are all the surname units in lowercase? Convention dictates that Newton, Ohm, etc. be capitalized. -- 98.216.104.10 ( talk) 14:43, 15 August 2020 (UTC)
Maybe move to SI derived units. It just sounds better. 2A02:C7D:3FB0:300:E895:45DB:31:1A0D ( talk) 18:40, 13 October 2020 (UTC)
I think 1 C is exactly 1/(1.602176634×10−19), which is 1/(unit of elementary charge: e). So how can it be a derived unit? I think necessary changes in effect since 20 May 2019 of SI is not reflected in this article... JSoos ( talk) 11:10, 6 November 2020 (UTC)
In the chart about meters per second, m/s is described as speed and velocity. From a bit of cursory research, velocity is meters per second (m/s), and speed is velocity without regard to direction, or the absolute value of velocity (|m/s|). Should other people agree, should this be changed or noted? Saltedcoffii ( talk) 13:19, 21 November 2022 (UTC)
JPF 2023-01-11: I'm not sure - I see this page for the first time - but please take a look for units of
- "magnetic moment": Equal to "magnetic dipole moment" with unit J/T ? Both quantities show different base units, but refer to the *same* Wikipedia article ...
- "magnetic rigidity": I don't know what that is, but the referred article names its unit: Volt, and later then (indeed) T*m ... The rigidity article seems irritating to me (I'm no particle physicist); nevertheless, please check the unit in *this* article. 91.16.152.248 ( talk) 21:24, 11 January 2023 (UTC)
Should we consider adding a mention of the decibel scale? The bel (B) is a unit derived from SI. BeniaminB ( talk) 22:10, 13 July 2024 (UTC)
![]() | Measurement List‑class ( defunct) | ||||||
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what about the byte like gigabyte and megabyte —Preceding unsigned comment added by 76.167.223.99 ( talk) 06:13, 29 September 2008 (UTC)
Hmmm. Are I'm infringing ones copyright by taking commonly used definitions??? Tobias Hoevekamp
Ah, here we go, perhaps Lee Daniel Crocker's comments in United States/President might reassure you. If not, perhaps this is a question for talk:Copyright?
-- dja
Yes, I don't see anything copyrightable here. Even if you took whole sentences out of the ISO specs, they're not copyrighted either--deliberately. That's the whole purpose of the ISO. --LDC
(Internation Standards (published by ISO) are copyright, the copyright is owned by ISO, they reserve all rights. There is no right to copy anything from an International Standard. Obviously this is often a problem if you want to implement, use, or descrribe one. Providing copyright free specifications is not the purpose of ISO. Alas. -- drj).
Are you sure that ISO waives their rights? ISO charges big bucks for most standards as a way to finance themselves. If these were really public domain, we would have seen a lot of them printed cheaply, or floating around the net, no? -- Robbe
Yes, some (OK, most) ISO specs are copyrighted--especially industrial standards. But they do grant explicit rights to the metric weights and measures stuff. I'll see if I can dig up a citation somewhere. --LDC
Woulnd't it be better to try to make this chart more free form, using indentation to get pre formatting, as with periodic table, so that it is easier to edit?
Although they are derived units, there are standard base units for derived quantities such as area (the are, as in "hectare") and the liter, these should be included, just as have been units like webers etc.
I'd do it, but frankly, I'm a bit put off by the table markup. Maybe I'll make an alternative table to demonstrate how I think it should be done.
And no, I don't think it's a violation of the copyright to transcribe facts, so long as you don't make an exact copy of the layout from the original. I saw someone address this issue recently in another context, I'll see if I can dig up the discussion and then post a link to it here.
-- dja
Something like this: SI derived units freeform table
I started by reading the HTML-formatted table with the character-based web browser "links" in a sufficiently wide terminal window, saving the formatted output to a file. I then passed it through the following perl one-liner to preserve the free formatted links, and to restore the superscripting:
perl -ne 's/|/ /g; s/[(S+s*S*s*S*)]?/ $1/g; s/(S+)?/ $1/g; s/(w)(-*d+)/$1$2/g; print' si_derived_units.txt > si_derived_units5.txt
Finally, I did some manual cleaning up in a text editor before copying and posting it.
FWIW, YMMV, and all that.
-- dja
Neither SI derived units freeform table nor SI derived unit look good to me. What I don't like is, that we are restricted to very basic mathematical formulations... -- th
Do you have an example of what would be more appropriate? Seems to me that one is going to run into such limitations with any tabular format. The freeform table is not intended so much for its prettiness (although I don't think it is downright *ugly* even so), but rather to make the layout more accessible and editable by people who are more interested in the content than in the minutiae of HTML markup. Such concern is fairly central to Wikis, in general.
-- dja
Problems with the freeform table: (a) It is difficult to get the alignment right, because the link brackets (4 chars) can turn into zero, one (the question mark), or three chars (? plus brackets). If somebody creates one of the dangling links on your page, the alignment changes and must be fixed. (b) Browsers may word-wrap PRE content, which makes the table almost unreadable. Mozilla does this. (c) SUP is not allowed inside PRE, and therefore most of the units are broken (m^2, m^-1, etc.). -- Robbe
(a) Granted, though perfect alignment isn't always necessary (b) OK (c) I see that this is so from
http://www.w3.org/TR/html4/sgml/dtd.html#pre.exclusion
Good thing I didn't change the main page too early. :-)
-- dja
what is a liter?
As_I_Understand_It, degree Celsius is NOT an SI unit, the Kelvin is. Anyone know how to confirm / refute this? SGBailey 10:34 Dec 12, 2002 (UTC)
The table suggests the "Celsius" is an unofficial unit of temperature. Shouldn't that be the "degree Celsius"? — Preceding unsigned comment added by 142.30.227.14 ( talk • contribs) 00:03, 29 April 2010 (UTC)
I dont see the dyne (symbol: dyn) mentioned here or on the force page. It appears to have a defined relationship with the newton. Is it a bastard unit of measure?
I have started changing some of the math formulas to use <math> constructs. I think this looks much better, and is not much more difficult to edit (see Wikipedia:TeX markup). If nobody objects, I will finish this off sometime soon. I agree that the freeform table looks pretty bad, and the html table isn't much better. I don't think the html table is too difficult to edit, but maybe I will format it in a way that makes it easier for people to understand how to edit. Or maybe I'll make my own attempt at a freeform table. We'll see... -- HN 21 May 2003
There are templates available e.g. [[Template:SI_derived_units]] and [[Template:SI_accepted_units]] which could be used to start this article. Would they be useful in this article? Ian Cairns 00:31, 8 Nov 2004 (UTC)
I propose that this be merged to Degree Celsius#Conversions. Jimp 14Oct05
It's already there, yes, but not in as concise a form. If we don't remove it from here it still may be worth duplicating it over there. You have a point, Gene, "this is a conversion within the International System of Units" however I wonder whether this is enough to warrant keeping the section here. The conversion is also covered in the SI derived units with special names table (as a mathematical formula). Is this not enough? There are a great number of things that might be called "quite relevant to the structure and usage of SI" (many of which may have just as good a reason to be included here) do we have room for them all? I say keep the details of particular units on their own pages, kelivins to Celcius being no exception. Jimp 21Oct05
Is there a reason why the SI base unit page says "...the fraction 1⁄273.16 (exactly)..." while the SI derived unit page says "t°C = tK − 273.15". I realize that 0.01 is a small amount, but they can't both be correct. TheAmigo42 ( talk) 22:06, 27 February 2008 (UTC)
All this chatter is irrelevant, as the Kelvin should not even appear in this list, as it is one of the seven basic SI units, NOT a "derived unit". Dumbhick ( talk) 13:09, 17 July 2008 (UTC)
Shouldn't the "Expression in terms of SI base units" be cd ^ -1 as it is 1/cd? -- I hate to register 12:43, 31 July 2006 (UTC)
Would it not be better and clearer to quote the Newton as being kg.m/s^2 rather than m.kg/s^2? After all Force is usually quoted as F=ma (mass x acceleration). Similar with Pascals. —Preceding unsigned comment added by 195.195.173.31 ( talk) 15:05, 6 November 2007 (UTC)
212.137.63.86 ( talk) 11:19, 6 August 2008 (UTC)
Correct me if I'm wrong, but I do not believe that E should be here. It's the symbol for the electromagnetic field, but not a unit of magnitude. It's comparable to T(time) and L(length) as opposed to being comparable to s(second) or kg(kilogram). I will go ahead and remove it on the grounds that it doesn't belong here. Feel free to revert back if I am wrong. I am a student and not a scientist. - 70.119.126.195 ( talk) 04:44, 22 November 2008 (UTC)
Specific Energy Density is the product of the specific energy of a material times its energy density. The higher the number, the more potential energy is contained in that substance. As the typical units of Specific Energy are m2/s2 or J/kg, and of Energy Density are kg/m·s2 or J/m3, so the product is equivalent to kg·m/s4 or J·J/kg·m3. Unfortunately there is no SI unit for this, but it is the best way of classifying a material by its energy content, since lower mass or less volume will increase the overall number. It's a pity there's no SI derived unit for this concept. May I name it? Surely I'm not the first to discuss it? But can we call it Jacobs? :)
-- TimeHorse ( talk) 19:18, 4 January 2011 (UTC)
I suggest adding 7 columns to the table: m, kg, s, A, K, Cd and mol, the values in each of these columns will be the exponent of the SI unit or 0 if that unit does not form part of the definition. For instance, Hertz would be 0, 0, -1, 0, 0, 0, 0; Newtons would be 1, 1, -2, 0, 0, 0, 0; Lumen would be 0, 0, 0, 0, 0, 1, 0; Volt would be 2, 1, -3, -1, 0, 0, 0; etc.
-- TimeHorse ( talk) 19:24, 4 January 2011 (UTC)
I propose to swap the order of the tables (to match the SI Brocure), so that Table 1 gives examples of the unlimited number of derived units and Table 2 is a list of specially-named derived units (so that the article discusses the general before the particular) Adamtester ( talk) 00:38, 14 January 2011 (UTC)
radians somehow cannot be expressed wouldn't that make it a base unit? —Preceding unsigned comment added by 79.71.100.247 ( talk) 22:56, 2 April 2011 (UTC)
The table stated incorrectly that 1 °C = 1 K - 273.15. What is meant is that 1 °C = 1 K, but that the degree Celsius is used for reporting temperatures relative to 273.15 K. Dondervogel 2 ( talk) 07:31, 5 January 2015 (UTC)
@ User:Dondervogel 2 1 °C = 1 K - 273.15 it is obvious. but 1 °C = 1 K is definitely wrong! °C can never be equal to K.
Δ°C= ΔK
~" aGastya" ✉ let’s talk about it :) 14:50, 18 February 2015 (UTC) Dondervogel 2 ( talk) 15:29, 18 February 2015 (UTC) I think what you mean is that the numerical value of temperature expressed in deg Celsius is never equal to the numerical value of temperature expressed in kelvin. I agree with this statement, but it is not what I said. What I said, in equation form, (and meant) is that the unit degree Celcius is identical the unit kelvin. Dondervogel 2 ( talk) 15:29, 18 February 2015 (UTC)
Yeah, they just depend in +273.15 but deg C isn't SI unit
~"
aGastya"
✉ let’s talk about it :)
11:22, 19 February 2015 (UTC)
N-m is for Torque as well as Energy too. Should not that too be added in the table? thanks! ~" aGastya" ✉ let’s talk about it :) 11:50, 18 February 2015 (UTC)
second inverse is there in table of "Named units derived from SI base units" metre inverse is names in table of "Some SI derived units" Why so? both of them should be in a same table, isn't it? And then also "Angular Frequency" is also missing in the table (second inverse) Thanks ~" aGastya" ✉ let’s talk about it :) 11:58, 18 February 2015 (UTC)
According to [ [2]], nautical miles (and by extension, knots) are acceptable non-SI units. Why aren't they on the page or the template? Is this an example of systemic bias against imperial units? — Preceding unsigned comment added by 161.149.102.86 ( talk) 06:20, 8 July 2016 (UTC)
The 'expression in terms of SI base units' for lumen per watt 'm−2⋅kg−1⋅s3⋅lm' should be changed into 'm−2⋅kg−1⋅s3⋅cd' in order to be consistent with the SI base unit table. — Preceding unsigned comment added by 176.127.191.90 ( talk) 08:47, 10 September 2016 (UTC)
An editor has asked for a discussion to address the redirect Planck electric potential. Please participate in the redirect discussion if you wish to do so. signed, Rosguill talk 17:36, 8 April 2020 (UTC)
Why are all the surname units in lowercase? Convention dictates that Newton, Ohm, etc. be capitalized. -- 98.216.104.10 ( talk) 14:43, 15 August 2020 (UTC)
Maybe move to SI derived units. It just sounds better. 2A02:C7D:3FB0:300:E895:45DB:31:1A0D ( talk) 18:40, 13 October 2020 (UTC)
I think 1 C is exactly 1/(1.602176634×10−19), which is 1/(unit of elementary charge: e). So how can it be a derived unit? I think necessary changes in effect since 20 May 2019 of SI is not reflected in this article... JSoos ( talk) 11:10, 6 November 2020 (UTC)
In the chart about meters per second, m/s is described as speed and velocity. From a bit of cursory research, velocity is meters per second (m/s), and speed is velocity without regard to direction, or the absolute value of velocity (|m/s|). Should other people agree, should this be changed or noted? Saltedcoffii ( talk) 13:19, 21 November 2022 (UTC)
JPF 2023-01-11: I'm not sure - I see this page for the first time - but please take a look for units of
- "magnetic moment": Equal to "magnetic dipole moment" with unit J/T ? Both quantities show different base units, but refer to the *same* Wikipedia article ...
- "magnetic rigidity": I don't know what that is, but the referred article names its unit: Volt, and later then (indeed) T*m ... The rigidity article seems irritating to me (I'm no particle physicist); nevertheless, please check the unit in *this* article. 91.16.152.248 ( talk) 21:24, 11 January 2023 (UTC)
Should we consider adding a mention of the decibel scale? The bel (B) is a unit derived from SI. BeniaminB ( talk) 22:10, 13 July 2024 (UTC)