RFC 6020, "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", October 2010

Errata ID: 3470
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Ladislav Lhotka
Date Reported: 2013-01-24
Verifier Name: Benoit Claise
Date Verified: 2013-02-12

Section 7.16.2 says:

An identity MUST NOT reference itself, neither directly nor 
indirectly through a chain of other identities.

It should say:

The derivation of identities has the following properties:

o It is irreflexive, which means that an identity is not derived from 
  itself.

o It is transitive, which means that if identity B is derived from A
  and C is derived from B, then C is also derived from A.

Notes:

The desired properties of identity derivation are not clearly stated. The discussion in the NETMOD mailing led to a general agreement that identity derivation is supposed to be irreflexive and transitive. These two properties together also eliminate the possibility of a circular derivation.

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