~~~ units such as the single and double and slant vertical lines.

Today, I doubt if chip manufacturers even bother or even know the difference... just like the £...

The MOP experts here in the US,1970's; who visited CARO found the info.

That set was custom made and not made with stock denominations for all the reasons I outlined (archived here) in my MOP posts. In other words the denom and monetary unit are central which, is not always the case with stock denoms in Europe where the monetary unit was mostly added on to the stock dnomination... and even then, those in the US who study the graver types and even how they were sharpened know which was first and which was machined and even high and low speed detection... Too much study for me and really not all is needed except for when there is doubt of fakes, counterfeits and recent creations suspected -- especially when older, crusty MOP is used while the original denominations saved...