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Re:The First Room-Temperature Ambient-Pressure Superconductor by xxpor on Tuesday July 25, 2023 @04:51PM (#36869303)
One catch would be the use of lead would restrict the use cases fairly heavily
Re:The First Room-Temperature Ambient-Pressure Superconductor by petsfed on Tuesday July 25, 2023 @05:01PM (#36869469)
Its not a dirty secret, but just like the rules on chemicals under the organic certification, if you can show that there's no way to do what you want to do with lead-free, you can get an exemption. I suspect that "significantly lowers the cost of power generation" would outweigh "contains lead".
Re:The First Room-Temperature Ambient-Pressure Superconductor by amatecha on Tuesday July 25, 2023 @05:15PM (#36869705)
Yeah, I just mentioned in another comment that there already exist exemptions such as server/networking hardware:

"Lead in solders for servers, storage and storage array systems, network infrastructure equipment for switching, signalling, transmission, and network management for telecommunications"

( https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A... )

Re:The First Room-Temperature Ambient-Pressure Superconductor by kibwen on Tuesday July 25, 2023 @07:07PM (#36870978)
> if you can show that there's no way to do what you want to do with lead-free

The bar is even lower than that. For example, bullets are still made of lead, not because it's necessary, but because it's cheap, and despite the fact that it contaminates the meat of the hunted animal with lead.

Re:The First Room-Temperature Ambient-Pressure Superconductor by hollerith on Tuesday July 25, 2023 @07:11PM (#36871009)
Tangentially, the US Army has completely stopped using lead in bullets. Their 5.56 NATO ammo has copper where the lead used to be (i.e., inside a brass jacket) which reduces performance because copper is only 2/3 as dense as lead.
Re:The First Room-Temperature Ambient-Pressure Superconductor by pnpnp on Tuesday July 25, 2023 @07:32PM (#36871179)
To be fair, the US Army puts a looooot of ammo in the ground, which can have pretty severe consequences.

The consumer market still uses it, which is probably a tiny fraction of what the military uses in training.

Re:The First Room-Temperature Ambient-Pressure Superconductor by kibwen on Tuesday July 25, 2023 @07:51PM (#36871315)
Copper bullets date back to the 80s, they're not a new development. Copper bullets have higher penetration despite having less mass, which makes them better against armored targets, and NATO still held on to lead for so long just because it's cheaper.
Re:The First Room-Temperature Ambient-Pressure Superconductor by Tuna-Fish on Tuesday July 25, 2023 @09:04PM (#36871880)
They date back further than that. In WW1, French troops were mostly shooting full copper/bronze shot. The reason was that it was cheaper and easier to mass-produce solid copper bullets than it was to increase the production of jacketed bullets by a similar amount, and with Germany excluded from naval trade, there was suddenly a lot more copper available on the market.
Re:The First Room-Temperature Ambient-Pressure Superconductor by hguant on Tuesday July 25, 2023 @07:54PM (#36871337)
Sorry, but this is entirely incorrect.

First, terms - brass is not used to "jacket" a bullet. Brass is used as the case material for the cartridge. Steel, and nickel plated steel are some times also used here. "Jacketing" (as in, Full Metal Jacket) refers to the material that wraps around the exterior of the projectile. As far as I'm aware, the material used here is almost always copper, or a copper alloy (cupronickel).

The US standard bullet is the M855. It's a lead core with a soft soft steel penetrator at the tip, that's jacketed with copper.

There's an advanced version of the M855, the M855A1, which is an entirely steel slug, jacketed with copper. This bullet has better terminal performance at longer ranges, and slightly better armour piercing capabilities.

The US army standard training round is the M193. It is a lead bullet jacketed with copper. Interestingly, it in many ways has better terminal performance than the M855 because this is the bullet the M16 and M4 rifles were designed around, and the M855 only exists because of NATO politics.

There are no bullets in the US inventory, to my knowledge, that use a copper core. Copper is simply far too expensive to be used at that scale, and, as you pointed out, reduces the weight of the projectile which has negative effects on terminal performance.

"Why are bullets jacketed in copper" you might be wondering here - when rifle cartridges were invented, they still used black powder, and all bullets were lead. When smokeless powder was invented, it became possible to have more explosive power per unit of volume. However, this had two negative effects - one, the lead projectile would either disintegrate, or became entirely inaccurate, at the speeds it was accelerated to. Second, the force of the bullet against the rifling of the barrel was rubbing away metal from the bullet, leaving lead deposits which fouled the gun and made it inaccurate. All steel bullets solved this problem, but increase the wear on the barrel. The solution was to coat (jacket) each bullet in a thin layer of copper, which was stiff enough to withstand the force of friction in air, while also softer than the steel barrel and reduced wear and tear on the rifles

Re:The First Room-Temperature Ambient-Pressure Superconductor by hollerith on Tuesday July 25, 2023 @08:18PM (#36871523)
I'll concede that my assertion that the jacket is brass might be incorrect. But you're about 13 years out of date when you write that "There are no bullets in the US inventory, to my knowledge, that use a copper core. Copper is simply far too expensive to be used at that scale . . ."

Photos of cross sections of the M855 and M855A1:

https://twitter.com/izlomdefense/status/1202516482082639872/...

Ignoring the jacket, M855 has a lead plug behind a steel penetrator. M855A1 has a copper plug behind a steel penetrator. So, I stand by my "copper where the lead used to be". I never said there wasn't a steel penetrator.

From https://en.wikipedia.org/wiki/5.56%C3%9745mm_NATO:

>For general issue, the U.S. Army adopted the M855A1 round in 2010 to replace the M855. The primary reason was pressure to use non-lead bullets. The lead slug is replaced by a copper alloy slug . . . The U.S. Marines adopted the Mk318 in early 2010 due to delays with the M855A1. This was a temporary measure until the M855A1 was available for them, which occurred in mid-2010"

As you probably know, most combat soldiers in the US Army and Marines carry a rifle that fires 5.56×45mm NATO, so it is probably the ammo type that the US military has the most of.

Re:The First Room-Temperature Ambient-Pressure Superconductor by hguant on Tuesday July 25, 2023 @09:37PM (#36872116)
This post is a master class in why you shouldn't get all your information from Wikipedia. Press releases are not reality.

Yes the M855A1 was developed and started operational testing in 2010. However, it wasn't available to anyone who wasn't forward deployed until...my memory says 2015. The M855 is still used on post because a) it's cheap, and ballistically similar to the M855A1 and b) the production lines at Lake City are still geared for them

The Marine corps didn't formally adopt the M855A1 until 2017/2018. Brass didn't like it because it broke the feed ramps on machine guns. There was a big procurement SNAFU about this.

Marine corps times article on the matter:

https://www.marinecorpstimes.com/news/your-marine-corps/2017...

I get that you're trying to be snide because you were so publicly wrong, but your tone here really just makes you sound like you're trying to sound smart about something you know nothing about. Something to consider. Frantic googling does not an expert make.

You're right about the copper core on the new model A1 - I thought it was steel entirely with thin jacket. I would argue that when, by weight, the majority of the bullet is steel, my original point still holds.

Re:The First Room-Temperature Ambient-Pressure Superconductor by hollerith on Tuesday July 25, 2023 @09:49PM (#36872192)
I worded my original assertion the way I did (lead replaced with copper) so that it would be true even if the majority of the bullet is steel.

>I get that you're trying to be snide because you were so publicly wrong, but your tone here really just makes you sound like you're trying to sound smart

Right back at you. I don't think I'm motivated by trying to sound smart, but rather by curiosity about the subject. Well, OK, half by wanting to sound smart (and win arguments) and half by curiosity.

In particular, I'm still curious about whether ammunition containing lead is still routinely used by the US military--if you still want to talk about it. I realize Wikipedia can be totally wrong. So far I haven't succeed in wringing information out of Google Search that would corroborate or support your assertion. When's the last time you (or someone you know to usually tell the truth) has observed M855 being used by the US military in significant quantities?

Re:The First Room-Temperature Ambient-Pressure Superconductor by hguant on Wednesday July 26, 2023 @03:04AM (#36874025)
Answering without doxxing myself is harder than I thought. The last time I was on a US military range, which to be fair was right before the pandemic so things probably have changed - we drew green tip (M855) from the range master. My understanding was that a) the steel targets were getting beat up by A1 and there wasn't any money to replace them and b) we weren't a combat group so we didn't rate the good shit.

EDIT TO ADD: I don't know if that qualifies as "quantities" and anecdotes are just that, but that's been my experience.

Re:The First Room-Temperature Ambient-Pressure Superconductor by hollerith on Wednesday July 26, 2023 @08:10AM (#36876337)
Thanks for taking the time to set me straight on that. I didn't realizes I would be posting misinformation when I decide to jump into the conversation.
Re:The First Room-Temperature Ambient-Pressure Superconductor by georgewh on Tuesday July 25, 2023 @08:16PM (#36871504)
M855A1 is copper core. Lead free was a requirement as lead contamination from ranges was becoming a problem. See: https://www.army.mil/article-amp/106710/picatinny_ammo_goes_...
Re:The First Room-Temperature Ambient-Pressure Superconductor by gbcfghhjj on Tuesday July 25, 2023 @11:58PM (#36872905)
>The US army standard training round is the M193. It is a lead bullet jacketed with copper. Interestingly, it in many ways has better terminal performance than the M855 because this is the bullet the M16 and M4 rifles were designed around

As I understood the standard M4 with 1:7 barrel can't shoot M193 accurately

Re:The First Room-Temperature Ambient-Pressure Superconductor by carabiner on Tuesday July 25, 2023 @05:01PM (#36869476)
Lead is used everywhere. Not in paint anymore but you can buy lead weights at hardware stores. Don't grind it up and put it in your muni water supply, but it's a household substance that is harmful if ingested, like many others.
Re:The First Room-Temperature Ambient-Pressure Superconductor by geph2021 on Tuesday July 25, 2023 @05:14PM (#36869681)
another example, you can still buy lead based solder, even at a local hardware store.
Re:The First Room-Temperature Ambient-Pressure Superconductor by lazide on Tuesday July 25, 2023 @06:22PM (#36870469)
Also lead acid batteries which have ~ 50 lbs of lead sulfide in them (which also releases toxic gas if melted!)
Re:The First Room-Temperature Ambient-Pressure Superconductor by pfdietz on Tuesday July 25, 2023 @06:46PM (#36870785)
Sulfate, perhaps.
Re:The First Room-Temperature Ambient-Pressure Superconductor by tehnub on Wednesday July 26, 2023 @04:46PM (#36884743)
Is lead based solder not standard? (I've never soldered.)
Re:The First Room-Temperature Ambient-Pressure Superconductor by pubby on Thursday July 27, 2023 @12:51AM (#36889059)
Both lead solder and lead-free solder are commonplace. Lead is standard in aerospace and military applications, while lead-free is standard in most products sold in the EU.
Re:The First Room-Temperature Ambient-Pressure Superconductor by marcosdumay on Tuesday July 25, 2023 @05:06PM (#36869555)
> you can buy lead weights at hardware stores

Those are often bismuth weights.

Re:The First Room-Temperature Ambient-Pressure Superconductor by JumpCrisscross on Tuesday July 25, 2023 @04:59PM (#36869436)
> the use of lead would restrict the use cases

Most people aren't licking the insides of their computer processors, fusion reactors, radio telescopes and MRIs.

Re:The First Room-Temperature Ambient-Pressure Superconductor by amatecha on Tuesday July 25, 2023 @05:02PM (#36869479)
It's more about producing toxic waste and contaminating the environment - no one's licking the solder joints in their electronics either, but you still have to use lead-free solder.

For instance in EU, https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A...

Canada, https://www.canada.ca/en/health-canada/services/environmenta...

USA, https://www.epa.gov/lead/learn-about-lead

Re:The First Room-Temperature Ambient-Pressure Superconductor by JumpCrisscross on Tuesday July 25, 2023 @05:08PM (#36869586)
> more about producing toxic waste

Compared to refining traditional conductors and recycling/disposing of used electronics?

> you still have to use lead-free solder

One, fumes. Two, people touch their solder and then grab a cookie.

We're premature. The results need to be proven. But the benefits of RTP superconductors is mindblowingly high enough that risks from lead contamination (far from a novel problem, I might add) can be safely ignored.

Re:The First Room-Temperature Ambient-Pressure Superconductor by amatecha on Tuesday July 25, 2023 @05:10PM (#36869619)
It's like fundamental best practice to always wash your hands thoroughly with soap if you handle leaded solder.

You might want to read more in the links I shared about the harmful effects of lead before "whatabouting" to other problems of electronics recycling/waste.

and yes, it's entirely possible this application would get an exemption from usual restrictions on lead. For example in the EU directive, one of the exemptions is:

> Lead in solders for servers, storage and storage array systems, network infrastructure equipment for switching, signalling, transmission, and network management for telecommunications

Re:The First Room-Temperature Ambient-Pressure Superconductor by JumpCrisscross on Tuesday July 25, 2023 @05:15PM (#36869701)
> fundamental best practice to always wash your hands thoroughly with soap if you handle leaded solder

But people don't, particularly students, and sometimes they also let their irons run too hot at which point fumes become an issue. Also, there is an easy alternative, so why not.

If the choice is lead superconductor or not, nobody is going to pause on a use case because there is lead. If they do, and if this is real, please let me know--I'd love to have them as competition.

> might want to read more in the links I shared about the harmful effects of lead before "whatabouting" to other problems of electronics recycling/waste

The point is, whether a RTP superconductor does or doesn't contain lead is irrelevant to its adoption. The advantages are too large. What current directives say are, similarly, irrelevant.

Re:The First Room-Temperature Ambient-Pressure Superconductor by amatecha on Tuesday July 25, 2023 @05:17PM (#36869727)
Oh, sure. You could have just said that then. You instead originally said something about "no one licks the insides of the computers", which isn't the reason lead in electronics/PCBs/etc. is restricted, and what I was pointing out.
Re:The First Room-Temperature Ambient-Pressure Superconductor by JumpCrisscross on Tuesday July 25, 2023 @05:18PM (#36869743)
Was being cheeky in response to OP claiming "the use of lead would restrict the use cases fairly heavily."
Re:The First Room-Temperature Ambient-Pressure Superconductor by refulgentis on Tuesday July 25, 2023 @05:21PM (#36869792)
Usually people who are making the argument you were making with the words you were using are signalling that lead is "lump of rock from center of nuclear reactor" dangerous. Honest to god, a lot of people believe this
Re:The First Room-Temperature Ambient-Pressure Superconductor by mrob on Tuesday July 25, 2023 @06:13PM (#36870373)
Soldering temperatures don't produce significant lead fumes. The fumes you see are flux fumes (which are also bad to inhale).

IMO, the most dangerous thing about lead solder is cleaning the iron. Both the common methods (damp sponge and brass wool) create many tiny little balls of solder that are hard to see and bounce about all over the place. Because of the high density of lead they're less affected by air resistance than you might expect, and they roll easily, so they can move surprising distances. They can easily end up caught in clothing, and from there fall into food. This will result in much higher lead ingestion than just touching solder then touching food.

I personally always use lead-free solder. If you have a good temperature controlled soldering iron it's nearly as easy to use as leaded solder.

Re:The First Room-Temperature Ambient-Pressure Superconductor by segfaultbuserr on Wednesday July 26, 2023 @01:16AM (#36873404)
Lead-free through-hole soldering is easy and practical. Unfortunately, for SMT prototyping (including reflow soldering), lead-free work is no longer that easy. Another problem, even in through-hole devices, is when you have large metal parts - a tough problem for RF/microwave circuits full of SMA and BNC connectors, backed by 1 or even 2 layers of solid ground planes, providing excellent a heatsink and a lot of cursing during work and rework. With lead-free solder, I found the iron needs to be cranked up to 420°C for a usable experience (but a larger iron tip may reduce that to a more reasonable level), and I don't know what temperature does it take to desolder them.

The last time I checked, low-temperature bismuth-tin alloy is only available as solder paste, unfortunately not available as flux-core solder wires (they're not really a good choice for connectors to begin with as the alloy is brittle, but I only need it to survive before the next prototype...)

Re:The First Room-Temperature Ambient-Pressure Superconductor by segfaultbuserr on Wednesday July 26, 2023 @12:54AM (#36873268)
> One, fumes.

It's trivial to experimentally demonstrate that solder fume contains almost no lead, the quantity is negligible. Claiming the contrary is the electronics equivalent of saying HTML is a programming language. Please don't do that again. The fume is indeed toxic, but it's due to the VOCs from the flux core, not the lead in the alloy.

A more solid (no pun intended) argument can be the hazards of debris. Furthermore, in my opinion, a newer and more serious problem of leaded solder today, in a workshop setting, is its use in solder paste. Solder paste and a reflow oven are required for prototyping any circuit boards with surface-mount components (SMT) - basically any modern circuit board today. Solder paste is a tube of toothpaste-like chemical mixture that contains tiny, micrometer-sized metal particles, mixed with sticky flux. If they're used without care, a solder paste spill is a sure way to contaminate the floor or work surface of your workspace. The sticky paste is also hard to wash away from skin.

Unfortunately, reflow soldering of surface-mount components can be really challenging, even more so when doing it by hand. Thus, classic lead-tin alloy is often used to reduce difficulties of assembly during workshop prototyping due to its technically superior properties. Switching to lead-free is only possible when you have a tightly-controlled and consistent work flow.

If you want lead-free, for small-scale prototyping and rework, a non-toxic bismuth-tin alloy is sometimes a good alternative to standard SAC305 lead-free solder thanks to its low melting temperature, which is one main reason that makes most lead-free alloys difficult to use (it even has considerable popularity in mass production of LED devices, as they are heat-sensitive). But its surface tension is slightly different, weakening the self-alignment effect of components during reflow soldering, increasing the chance of defective joints - a concern in prototyping. Its brittle nature also increases failure rates in the field, among other caveats.

Lead is really a gift from the devil.

Re:The First Room-Temperature Ambient-Pressure Superconductor by petertodd on Wednesday July 26, 2023 @06:35AM (#36875428)
> Solder paste and a reflow oven are required for prototyping any circuit boards with surface-mount components (SMT) - basically any modern circuit board today.

This is incorrect. You can easily do small scale work with almost all SMT components without solder paste. Solder paste is required for automated assembly processes. But almost anything done by hand can also be done with conventional solder.

Source: I worked as an electronics designer for a few years, and assembled prototypes and small production batches by hand with SMT parts (0603's, TTSOPS, etc) every day.

The one exception is BGA devices, because the solder pads are underneath the device. But doing those by hand requires precise alignment that is difficult enough that few people do it. Also, for smaller BGA devices with fewer pins, skilled operators can still solder them in place with a heat gun by covering the pads with solder and flux and just melting them into place.

Re:The First Room-Temperature Ambient-Pressure Superconductor by jacquesm on Wednesday July 26, 2023 @07:04AM (#36875665)
I know two people (one of which is here on HN) who do fairly large BGAs by hand, I wonder if that skill is really that rare. I couldn't do it myself though, I did try but for some reason I can't make it work reliably enough to risk it on stuff that matters.
Re:The First Room-Temperature Ambient-Pressure Superconductor by segfaultbuserr on Wednesday July 26, 2023 @07:14AM (#36875766)
> basically any modern circuit board today [...] (0603's, TTSOPS, etc) [...] But almost anything done by hand can also be done with conventional solder.

I disagree. I don't consider 0603 passives and TSSOP packages "modern" anymore. Of course these components can be hand soldered with ease (possibly at top quality with the aid of a microscope). Unfortunately, even simpler ICs like DC-DC controllers are gradually abandoning TSSOP and QFP in favor of DFN, QFN, and LFCSP in recent years. These packages are all leadless, and frequently with thermal pads at the bottom. An older term for leadless packages is BTC - Bottom Termination Components [1]

After multiple failed QFN soldering attempts, I switched to ordering stencil, solder paste, and a hot plate. It worked perfectly on my first attempt, so I never looked back.

Unless you have top 10% soldering skills, which I don't (experienced smartphone repair technicians seems to have mastered the art of QFN), I found solder paste is required for maintaining your sanity for leadless packages. Furthermore, without reflow soldering, prototype assembly can be very time-consuming and takes hours, especially when you need 3 or more prototypes.

Occasionally, leadless packages also have optional difficulties turned on, completely eliminating the possibility of hand soldering, such as multiple pads for different nets (to minimize parasitic inductance), or having two layers of contacts, one row on the exterior and on row on the interior.

> You can easily do small scale work with almost all SMT components without solder paste. [...] The one exception is BGA devices

And DFN, and QFN, and LFCSP, and...

Thanks to industrial and automotive users, some ICs still have QFP versions that are friendly for hand operation due to their vibration resistance, but you sometimes have to pay a premium.

Finally, even plain-old QFP chips have bottom thermal pad these days (in that case, you can manually apply a blob of solder on the PCB and reflow again with a hot air gun, but manually apply a drop of paste is easier to work with).

[1] But these days it would make people think it's some kind of a Bitcoin mining ASIC. BTW, the last time I've checked, these ASICs are indeed QFN, so one can say they're BTC BTC chips...

Re:The First Room-Temperature Ambient-Pressure Superconductor by amatecha on Wednesday July 26, 2023 @01:39PM (#36881652)
Why is this being downvoted into oblivion? It's a completely valid, good-faith point explaining why lead has restrictions on its uses other than "someone might lick it"... It would be nice if people actually responded and vocalized their disagreement or described the flaws in my reasoning, rather than just suppressing my message.
Re:The First Room-Temperature Ambient-Pressure Superconductor by phatskat on Tuesday July 25, 2023 @04:59PM (#36869437)
> fairly heavily

Not being in sciences I can’t tell if this sentence is legit or you just got a good joke in there

Re:The First Room-Temperature Ambient-Pressure Superconductor by reaperman on Tuesday July 25, 2023 @05:01PM (#36869470)
For the benefits of superconduction, I imagine RoHS exemptions would be made.
Re:The First Room-Temperature Ambient-Pressure Superconductor by fijiaarone on Tuesday July 25, 2023 @05:17PM (#36869731)
If you think lead is scary, wait till you hear about carbon dioxide.
Re:The First Room-Temperature Ambient-Pressure Superconductor by tga_d on Tuesday July 25, 2023 @05:31PM (#36869858)
I mean, modulo edge cases, lead is a lot scarier than CO2; it's only because of the ridiculously obscene quantities of CO2 being produced that it's a more immanent threat. There's obviously not enough information yet to weigh the value/consequences of the amount of lead used here, but if your measure of whether something is a good idea for mitigating carbon emissions is just "it's not carbon emissions", you're going to find yourself kicking a can a bit down the road, or (much) worse.
Re:The First Room-Temperature Ambient-Pressure Superconductor by eternityforest on Tuesday July 25, 2023 @11:49PM (#36872845)
Maybe they could pack it into epoxy encapsulated modules of standard size, so you could always reuse it in another motor or transformer or what have you, assuming you were willing to disassemble the scrapped gadget?
Re:The First Room-Temperature Ambient-Pressure Superconductor by labster on Tuesday July 25, 2023 @10:03PM (#36872281)
If you think CO2 is scary, wait til you hear about methyl mercury.
Re:The First Room-Temperature Ambient-Pressure Superconductor by SomeRndName11 on Wednesday July 26, 2023 @03:42AM (#36874279)
If you think carbon dioxide is scary, wait for your cup of Pepsi. (Low toxicity of CO2 is actually one of the reasons it is not treated seriously enough).
Re:The First Room-Temperature Ambient-Pressure Superconductor by Roark66 on Tuesday July 25, 2023 @05:59PM (#36870194)
Cobalt is way more toxic than lead and yet every consumer grade lithium ion battery contains it. The fact something is toxic is not that important. What is that we manage the end of life for the products it contains responsibly.
Re:The First Room-Temperature Ambient-Pressure Superconductor by rezonant on Tuesday July 25, 2023 @06:47PM (#36870795)
Well yes and that its properly contained or otherwise shown to not pose an ingestion or undue exposure risk
Re:The First Room-Temperature Ambient-Pressure Superconductor by sheepscreek on Tuesday July 25, 2023 @07:09PM (#36870986)
This is a phenomenal find in any case.

As for how to avoid lead poisoning, coat the lead with a thin layer of some substance, perhaps a plastic or rubber that doesn’t affect its magnetic capabilities.

Or perhaps they can galvanize it with safer metal, leaving a really small part exposed.

Re:The First Room-Temperature Ambient-Pressure Superconductor by throwawaymobule on Wednesday July 26, 2023 @07:48AM (#36876118)
I think people are talking about RoHS rather than practical danger. Since RoHS is incredibly strict about quantities, e.g. if you can mechanically seperate a piece of the widget, that's what gets measured.

It'd likely be exempt though.