Ed Sirett wrote:

That is quite some ammendment. We have gone from don't unless the
manufacturers say you must to do what you like unless the manufacturers
say what you must do.

While both texts are unambiguous when read carefully, they're not
exactly a model of lucidity. Quite possibly the sense of the original
one was accidentally reversed - I've certainly seen that happen when
there's too long a chain between programmers and technical writers and a
complex concept to be defined.

Pete