We need to state how readers distinguish between normative and non-normative content consistently and clearly in both specs.  The SML spec currently marks some sections non-normative explicitly, leading a reader to the conclusion that the rest is normative; the SMLIF spec marks some sections normative, some non-normative, and leaves the rest ambiguous (including the schema).

Proposal: add following to Notational Conventions section accompanying the 2119 text (editorial word-smithing by editors explicitly allowed if it improves clarity)

All content in this specification, including but not limited to text, schema, and appendices, is normative except the following:
- content explicitly marked non-normative 
- content referred to as an example

(end of proposed added text) 

Where entire sections are to be marked, they should be marked consistently.  I recommend doing so in the heading, ala SML Appendix C.  This means for example that SML 8 (which is marked in text but not in its heading) must be changed.