HTML5 `<link rel=“shortcut icon” />`

Question

The WHATWG document for HTML5 says that the rel attribute must contain values that are space-separated, and then it gives a table of allowed values.

Answer 1

From the same WHATWG document:

For historical reasons, the icon keyword may be preceded by the keyword "shortcut". If the "shortcut" keyword is present, it must be come immediately before the icon keyword and the two keywords must be separated by only a single U+0020 SPACE character.