Code to be retained in the virtual document of the host.
Range of the foreign code relative to the original source.
null is used internally to represent a leftover host code after extraction.
Shift due to any additional code inserted at the beginning of the virtual document (usually in order to mock the arguments passed to a magic, or to provide other context clues for the linters)
Foreign code (may be empty, for example line of '%R') or null if none.