Patrick Durusau raises some issues about the nature of YAML and its suitability as a normative reference here: https://lists.oasis-open.org/archives/camp-comment/201309/msg00010.html

I noticed the normative reference to YAML under 1.8 Normative
References.

Not being familiar with it, I followed the link.

• From "Status of this Document" I read:

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This specification is a draft reflecting consensus reached by members
of the yaml-core mailing list. Any questions regarding this draft
should be raised on this list. We expect all further changes to be
strictly limited to wording corrections and fixing production bugs.
*****

So the YAML normative reference is to a draft dated 2005-01-18, that
reflects a "consensus" of members of a mailing list.

Is that a fair characterization?

There is no formal organization charged with its maintenance and no
known process other than email "consensus" as far as any changes?

As I said in a post earlier today:

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First, draft work should never be used in normative references at all.
Under any circumstances. As the TC Process notes (Section 1, w:

*****
"Normative Reference" means a reference in a Standards Track Work
Product to an external document or resource with which the implementer
must comply, in order to comply with a Normative Portion of the Work
Product.
*****

Note the "must comply" language.

Drafts by their very nature change and reliance on a draft invites a
lack of interoperability.
**********

• From examining the draft it is clear that conformance to YAML, a
  mailing list consensus draft, is critical for use of this standard.

The only solution that comes to mind, given that YAML states it can be
copied if not modified, would be to include a copy of YAML 1.1 as an
appendix and cite that appendix as your normative reference.

That fixes the text of YAML 1.1 to be what is included in the appendix
and provides implementers with a stable target for their implementations.

If YAML has not been modifed since its "final draft" date of
2005-01-18, it should be stable enough to not burden the TC with too
many maintenance duties.