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Comment by kseistrup | Hacker News Reader

They're more difficult to fake.

If the doctor prescribes 10 tablets, the user could be tempted to add a zero and thus get 100 tablets instead of 10. It's more difficult to turn an X into a C.

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But you can add a C just as easily as adding a zero, and now you've turned 10 into 110 or 90 depending on whether there was space before or after the X. I guess adding a D or M would be a bit more suspicious.

I never claimed it was impossible, just more difficult. Prevention of misreading is more important thar prevention of forgeries, I assume, and any misread og forged number would also have to match existing packaging sizes.

Adding a c is hardly more difficult than adding a 0.

Matching packaging sizes is not necessary - I have had prescriptions that do not match packaging sizes many times - they will cut up sheets or transfer to other containers as needed.

That's not universal. In my country, prescription medicine can only be sold in sealed boxes. Fractioning or tranfering to a different container is expressly forbidwn by law, so doctors always prescribe a number of boxes, not of pills. This makes a little more difficult to forge prescriptions.

This applies to the entire EU/EEA, too.

That must be recent, as it certainly was not the norm in the UK even prior to Brexit. For some medicines, UK pharmacists are required to split packs as needed to give exactly the number of pills prescribed.

I can't find anything to suggest EU rules prevents split packs - I do see there was a tightening of the rules on how to treat packs if dispensing split backs a few years ago, but nothing since. Do you have a source?

EDIT: At least as late as per the False Medicines Directive going into force in 2019, split pack dispensing was explicitly allowed - the FMD set out rules for the controls required to do so. E.g. the original container can not leave the dispensary until its entire content is used, and the pharmacy can't re-sell or supply other pharmacies with it.

[In fact, I just got a prescription filled and received 12 pills in a pack consisting of one full blister pack and a carefully cut out piece with 2 pills; but again in the UK so it could be there are newer EU regulations though I haven't seen any]

If it's prescribed as number of boxes it changes nothing, as it's then just the number of boxes you need to alter instead of number of pills.

The cited text has an extra detail:

  «… and it is customary to draw a line above all the letters making up the number, the dots of i and j being put above this line; for example, xviij»

So, XVIII would have been written likes this:

  _____
  XVIII
  -----

Lines would clearly delineate the beginning and the end of the number. This is how I have written the Roman numerals since school.

So, if the script had X written that way, adding a C, would have also required both lines to be extended. Not impossible to forge, but an extra effort nevertheless.

Extending a straight line sounds like the easiest part of the process compared to reproducing a letter so that it matches the handwriting. As an indicator of error this seems to work fine, but to prevent fraud it seems marginal at best.

Getting a prescription for 90 pills instead of 100 would presumably raise suspicion.

Probably depends, my prescriptions seem to be 90 days.

Why? If I'm prescribed a course of something for 90 days, I will get 90 pills, even if the packs have 100.

It might differ by location, but here (I'm in the UK), it's not unusual to e.g. get 14 pills of antibiotics if prescribed a two week course even if the package is in units of 10, for example.

Did one need a prescription to buy medicine in 1919?

It seems that prescription drugs were established in 1938 in US and in 1946 in UK.

https://en.wikipedia.org/wiki/Durham%E2%80%93Humphrey_Amendm...

Well, one can turn X into XX or XXX... And handwritten prescriptions have become rare where I live, these days.

And as per the instruction of 1919 "it is customary to draw a line above all letters making up the number, the dots of i and j being put above the line" (in other words, the horizontal line is directly above v, x, c, and so on but between the dot of i and j and the lower part of the letter).

I think this way it is difficult to add more Roman digits like x to fake a higher amount than prescribed.

The letter j seems to be an additional security because i as a letter is narrow and one could perhaps squash in one or two more i's. The instruction also mentions that the number of dots is important, if the number of i and j is not the same as the number of dots above the line, the apothecary should assume an error.

What prevented someone from just extending the line?

> I think this way it is difficult [...]

It's just difficult, but not impossible.

This said, such tampering is in my jurisdiction punishable by law (Art. 251 Forgery of a document), see https://www.fedlex.admin.ch/eli/cc/54/757_781_799/en#art_251

I am sure in Common Law jurisdiction forgery of documents is also punishable.

So such things are defended by a two-pronged approach: Make it difficult and forbid it.

Someone forging a number is already going to the trouble to find seclusion so that they are unobserved, and to try to match the writing instrument (color, stroke and texture) and the handwriting of the existing digits.

A horizontal square bracket would have been a more effective deterrent than just a line.

So find a time machine and travel back and tell the people of your superior solution.

scnr

My point is more that the people of the past weren't stupid; they didn't believe that a horizontal line couldn't be easily extended by a forger to hang over newly added digits. Rather, our explanation today is lacking; there must have been some other reason for the practice. Or no reason other than that someone stated it and it become something that is always done that way.

Checks are quite foolproof too - spelling out the number (a hundred eighty eight) and writing the number (188), like on checks.

The paragraph you mention seems to worry more about mistakes more than tempering attempts though (taking 10x the dose prescribed could indeed be problematic)

The important part there is the termination characters. "Dollars" / "Pounds only" etc. and the decimal point (though that's easier to turn into a comma and make into thousands... Funnily enough the German way of using comma as the decimal separator avoids this)

Yeah, we've tried null-terminated strings and it wasn't fun. Better use a more explicit, highly visible character.

Polish still regularly does this for contracts and all kinds of legal document.

I regularly see verbiage like "person A promises to pay person B 100 (in words, one hundred) zloty upon termination of this contract."

It's easy to turn X into XX (20) or XL (40) or XC (90).

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