See ยง6.5 of the ISO/IEC Directives Part 2. Notes, examples, and footnotes are all considered “informational”, as opposed to “normative”.
For notes and examples:
Notes and examples integrated in the text of a document shall only be used for giving
additional information intended to assist the understanding or use of the document. They shall
not contain requirements (“shall”; see 3.3.1 and Table H.1) or any information considered
indispensable for the use of the document, e.g. instructions (imperative; see Table H.1),
recommendations (“should”; see 3.3.2 and Table H.2) or permission (“may”; see Table H.3).
Notes may be written as a statement of fact.
For footnotes:
Footnotes to the text give additional information; their use shall be kept to a minimum. As is
the case for notes and examples integrated in the text (see 6.5.1) footnotes shall not contain
requirements or any information considered indispensable for the use of the document.
However, note that footnotes to figures and tables can contain requirements.