RFC Errata
RFC 8659, "DNS Certification Authority Authorization (CAA) Resource Record", November 2019
Source of RFC: lamps (sec)
Errata ID: 7139
Status: Reported
Type: Technical
Publication Format(s) : TEXT
Reported By: Brian Dickson
Date Reported: 2022-09-02
Section 4.2 says:
parameters = (parameter *WSP ";" *WSP parameters) / parameter parameter = tag *WSP "=" *WSP value tag = (ALPHA / DIGIT) *( *("-") (ALPHA / DIGIT)) value = *(%x21-3A / %x3C-7E)
It should say:
parameters = (parameter *WSP ";" *WSP parameters) / parameter parameter = parameter-tag *WSP "=" *WSP parameter-value parameter-tag = (ALPHA / DIGIT) *( *("-") (ALPHA / DIGIT)) parameter-value = *(%x21-3A / %x3C-7E)
Notes:
1. Original text uses "tag" and "value" in the ABNF is ambiguous or conflicting with the usage of "tag" and "value" in terms "Property Tag" and "Property Value" (which are in the main CAA context).
2. The text for "tag" (meaning Property Tag) in 4.1.1 reads:
Tag: A non-zero-length sequence of ASCII letters and numbers in
lowercase.
3. The Tag definition above does not have an ABNF definition. This can (and does) lead to confusion for implementers.
The above change to the ABNF removes the ambiguity, without changing the meaning of the ABNF itself.