Re: QUIT and ABORT

The standard contains the list of standard words, and the behavior of
each standard word is well specified (as far as a standard program
concerns).

True, and verifiable.

(by design; of course, the standard may contain mistakes)

You mean: Will contain mistakes :--)

Therefore, the behavior of a standard system can be falsified using
standard program examples. That is, if and only if the system deviates
from the specified behavior, this can be demonstrated by some standard
program.

What exactly do you want to do with this? It is not possible to test
all possible programs using all available words (e.g., we can always
add another word to a program). Thus the clause gives no guarantee
to a user and does not allow the vendor to claim anything.
Simple example:
A `standard program` from user A returns the wrong result. User A
claims this is because the Forth system from vendor B contains a
bug.
-marcel