ETA Questions: Interpretation of the "Changes in Level Are Not Permitted" Requirements

2) Where the Standard says "Changes in level are not permitted", such as 304.2 for turning spaces:

Here the standard is followed by an unenforceable advisory that says, "As used in this section, the phrase ‘changes in level’ refers to surfaces with slopes and to surfaces with abrupt rise exceeding that permitted in Section 303.3." It appears that the advisory changes the meaning of the phrase "Changes in level are not permitted," at least "As used in this section," so that qualified changes in level are allowed. Since the explanation is only found in Advisory 304.2 and not in the actual text of the Standard, can it be relied upon as valid?