The table in the article makes this look complicated, but it really isn't. All the cases in the article can be grouped into two families: - The JS/Go/Rust fami

The table in the article makes this look complicated, but it really isn't. All the cases in the article can be grouped into two families: - The JS/Go/Rust family, which treats $ like \z and does not support \Z at all - The Java, .NET, PHP, Python family, which treats $ like \Z and may or may not (Python) support \z. \Z does away with \n before the end of the string, while \z treats \n as a regular character. For multiline $ the distinction doesn't matter, because \n is the end. Really the only deviation from the rule is Python's \Z, which is indeed weird.