He did it on plastic CD cases, not oil. The oil in the beginning of the article was just for explaining the refraction that happens with the ridges in the structure.
I just found out you may - even in current HTML use entity references in attribute values, it’s just you don’t have to anymore, when the ampersand is not ambiguous.
The spec states it as: “Attribute values are a mixture of text and character references, except with the additional restriction that the text cannot contain an ambiguous ampersand.”
Whereas in the the days before HTML5 this has been mandatory.
> HTML 4.01 Specification – Appendix B.2.2 “Ampersands in URI attribute values”
> Unfortunately, the use of the “&” character to separate form fields interacts with its use in SGML attribute values to delimit character entity references.
You're supposed to escape & anywhere in HTML, not just in text nodes. If you don't (and many don't) it'll probably work, but browser first tries to interpret it as a start of an entity anyway. Even if it is inside a href etc.
In HTML escaping & is kind of optional and the browser just tries to figure out what you mean, but if you are doing things properly you should use & in href attributes.
The authorities are saying they don't want to see any trash at all, regardless of volume. Imagine 100 sheets of paper vs 100 AA batteries. The batteries have much more volume, but the sheets of paper cover a much larger area so there's much more visible trash.
The biggest difference, is Uber has vehicles around the world. So there's more data from countries with different rules from the US. Signage is definitely different between the US and Europe.