global

def boilerplate(key)
  ret = ''
  case key.downcase
  when /\Abcp14(info)?(\+)?(-tagged)?\z/i
    if $1
      ret << <<RFC8174ise
Although this document is not an IETF Standards Track publication, it
adopts the conventions for normative language to provide clarity of
instructions to the implementer.
RFC8174ise
    end
    ret << <<RFC8174
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED",
"MAY", and "OPTIONAL" in this document are to be interpreted as
described in BCP 14 {{!RFC2119}} {{!RFC8174}} when, and only when, they
appear in all capitals, as shown here.
RFC8174
    if $2
      ret << <<PLUS
These words may also appear in this document in
lower case as plain English words, absent their normative meanings.
PLUS
    end
    if $3
      ($options.v3_used ||= []) << "** need --v3 to tag bcp14"
      ret << <<TAGGED

*[MUST]: <bcp14>
*[MUST NOT]: <bcp14>
*[REQUIRED]: <bcp14>
*[SHALL]: <bcp14>
*[SHALL NOT]: <bcp14>
*[SHOULD]: <bcp14>
*[SHOULD NOT]: <bcp14>
*[RECOMMENDED]: <bcp14>
*[NOT RECOMMENDED]: <bcp14>
*[MAY]: <bcp14>
*[OPTIONAL]: <bcp14>
TAGGED
    end
    ret
  when /\Arfc\s*7942(info)?\z/i
    if $1
      ret << <<INFO
(Boilerplate as per {{Section 2.1 of RFC7942}}:)

INFO
    end
    ret << <<RFC7942
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of
this Internet-Draft, and is based on a proposal described in
{{?RFC7942}}.  The description of implementations in this section is
intended to assist the IETF in its decision processes in
progressing drafts to RFCs.  Please note that the listing of any
individual implementation here does not imply endorsement by the
IETF.  Furthermore, no effort has been spent to verify the
information presented here that was supplied by IETF contributors.
This is not intended as, and must not be construed to be, a
catalog of available implementations or their features.  Readers
are advised to note that other implementations may exist.

According to {{?RFC7942}}, "this will allow reviewers and working
groups to assign due consideration to documents that have the
benefit of running code, which may serve as evidence of valuable
experimentation and feedback that have made the implemented
protocols more mature.  It is up to the individual working groups
to use this information as they see fit".
RFC7942
  else
    warn "** Unknown boilerplate key: #{key}"
    "{::boilerplate #{key}}"
  end
end