RFC 7950, "The YANG 1.1 Data Modeling Language", August 2016

Note: This RFC has been updated by RFC 8342, RFC 8526

Errata ID: 5663
Status: Rejected
Type: Technical
Publication Format(s) : TEXT
Reported By: Ebben Aries
Date Reported: 2019-03-18
Rejected by: Joel Jaeggli
Date Rejected: 2019-10-07

Section 14 says:

deviate-delete-stmt = deviate-keyword sep delete-keyword-str optsep
                      (";" /
                       "{" stmtsep
                           ;; these stmts can appear in any order
                           [units-stmt]
                           *must-stmt
                           *unique-stmt
                           *default-stmt
                       "}") stmtsep

It should say:

deviate-delete-stmt = deviate-keyword sep delete-keyword-str optsep
                      (";" /
                       "{" stmtsep
                           ;; these stmts can appear in any order
                           [units-stmt]
                           *must-stmt
                           *unique-stmt
                           *default-stmt
                           [config-stmt]
                           [mandatory-stmt]
                           [min-elements-stmt]
                           [max-elements-stmt]
                       "}") stmtsep

Notes:

Section 7.20.3.2 specifies all permitted substatements for the "deviate" statement however the ABNF grammar specifies different valid substatements per deviate argument. The "delete" argument is one such that only contains a subset of what is defined in the substatement table in this section.

The errata mentioned at: https://www.rfc-editor.org/errata/eid5489 is meant to correct the following statement

"""
The argument "delete" deletes properties from the target node. The
properties to delete are identified by substatements to the "delete"
statement.
"""

However this either needs to be a per argument table or ABNF correction
--VERIFIER NOTES--
Martin Bjorklund wrote:

I agree that the document needs clarification, and the yang-next issue
will take care of that. The document needs a clarification that the
refers to the grammar, or perhaps different substatement tables for
add/replace/delete.

Meanwhile, I think that this errata should be rejected.

rob wilton and robert varga wrote:

Hi Ebben,

I've always taken the ABNF to list the definitive sub-statements that are allowed for the various deviate "add", "replace", or "delete" options. Perhaps the RFC could state this more explicitly. Perhaps raise an issue on the YANG Next issue tracker to clarify this (https://github.com/netmod-wg/yang-next/issues) and it might get discussed tomorrow.

I agree.

Proposed statements are simple cases, for which 'deviate replace' can be
used to specify the correct value -- for example remove 'min-elements'
by replacing it with 'min-elements 0'.

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