[rfc-i] BCP/STD references

[cabo at tzi.org (Carsten Bormann)]

I just had a look at RFC 7749.  This contains a reference:

   [BCP13]    Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, January 2013,
              <http://www.rfc-editor.org/info/bcp13>.

bcp-index.txt says:

0013 Multipurpose Internet Mail Extensions (MIME) Part Four:
     Registration Procedures. N. Freed, J. Klensin, T. Hansen. December
     2005. (Format: TXT=74243 bytes) (Obsoletes RFC2048) (Also RFC4289,
     RFC6838)

Hmm, different title.  OK, RFC 4289 and RFC 6383.  Let's see:

4289 Multipurpose Internet Mail Extensions (MIME) Part Four: Registration
     Procedures. N. Freed, J. Klensin. December 2005. (Format: TXT=21502
     bytes) (Obsoletes RFC2048) (Also BCP0013) (Status: BEST CURRENT
     PRACTICE) (DOI: 10.17487/RFC4289)

6838 Media Type Specifications and Registration Procedures. N. Freed, J.
     Klensin, T. Hansen. January 2013. (Format: TXT=72942 bytes)
     (Obsoletes RFC4288) (Also BCP0013) (Status: BEST CURRENT PRACTICE)
     (DOI: 10.17487/RFC6838)

So is this a reference to RFC 6383 only (then why is is labeled BCP13,
implying this is about the BCP as a whole) or to both?  Section 4.8.6.3
of RFC 7322 tells me I need to put in all RFCs for a BCP or STD
reference.  (Unfortunately, it doesn't really tell me how to handle,
say, STD9, which is one well-ripened standard and half a dozen "updates"
documents.)  If this isn't done for the RFC editor's own documents, is
that maybe a hint that 4.8.6.3 isn't as practical as it needs to be?  Or
is it just an artifact of old tooling?

Background for my question: I'd like to be able to do a {{?BCP0013}}
(i.e., add an informative reference to BCP13) in kramdown-rfc and have
that handled entirely automatically*).  So far I have pushed this back
because I couldn't find a way to do this in RFCXMLv2.  Now we'll get
<referencegroup>...

Gr??e, Carsten

*) There is also the question whether someone will maintain a references
library like the one for RFCs on xml2rfc.ietf.org.  But one question at
a time.  https://github.com/cabo/kramdown-rfc2629/issues/5