There are multiple occurrences of normative terms ("must", "should" as defined in RFC2119) in the non-normative Extensibility section and its subsections that inherit the non-normative status of its parent. By convention, for consistency and clarity, non-normative sections typically do not use any normative terms.
Maybe this issue could be addressed by adding a note below the "This section is non-normative." statement to clear any confusion. For example:
Note: This section and its subsections are marked as non-normative but provide guidance to extension specification authors using normative language. From implementers' point of view, this section and its subsections are considered informative.
There are multiple occurrences of normative terms ("must", "should" as defined in RFC2119) in the non-normative Extensibility section and its subsections that inherit the non-normative status of its parent. By convention, for consistency and clarity, non-normative sections typically do not use any normative terms.
Maybe this issue could be addressed by adding a note below the "This section is non-normative." statement to clear any confusion. For example: