W3c is the human body that tries to standardize these things, they publish The foundations, then programmers publish their rendering motor to interpret These procedures. Here is some code that I a short while ago wrote. I imagine that it offers a basic explanation of combining course/ID names with pseudoclasses. https://naturalbookmarks.com/story19424188/everything-about-prestashop-seo-automatic-hreflang-tags-canonical-tags-on-all-pages