Re: [netmod] IETF 108: Summary of insignificant whitespace changes and versioning

Martin Björklund <> Tue, 11 August 2020 14:46 UTC

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Date: Tue, 11 Aug 2020 16:45:56 +0200
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From: Martin Björklund <>
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Subject: Re: [netmod] IETF 108: Summary of insignificant whitespace changes and versioning
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"Joe Clarke \(jclarke\)" <> wrote:
> At the IETF 108 virtual meeting, Lada asked about what would happen if
> he converted a YANG module to YIN syntax (or vice versa, or to some
> other format).  This was during the discussion of the issue of what
> should happen if a module changes and the only changes are
> insignificant whitespaces (e.g., strip trailing spaces, change line
> length of descriptions, etc.).
> The authors/contributors discussed on this on our weekly calls, and we
> propose:
> If a module changes and those changes are only insignificant
> whitespace changes and the syntax of the module remains the same
> (i.e., YANG to YANG, YIN, YIN, etc.), a new revision of the module
> MUST be created.  If you are using YANG semver as your revision
> scheme, you MUST apply a PATCH version bump to that new module
> revision to indicate an editorial change.
> The reasoning behind this decision is that it makes it very clear and
> unambiguous to consumers that this module has been consciously
> changed, and those changes are only editorial.  This way one won’t be
> concerned if they note that a module of a given syntax with the same
> version but different checksums and diffs wasn’t otherwise
> manipulated.

I think this is the wrong way to go.  I clean up formatting issues all
the time, including IETF modules.  I am pretty sure that if you
retrieve modules like "ietf-interfaces" or "ietf-yang-types" from
different vendors' products, you will get modules with differences in
whitespace - and this is not a problem AFAIK.

I think it is ok that a simple "diff" show whitespace changes in this
case.  I don't think it leads to any real problems.

> That said, if a module changes format from one syntax to another but
> maintains semantic equivalency, then the revision and YANG semver MUST
> be the same.  In that case, one will use the extension to realize that
> this module file cannot be directly compared to one of another syntax
> without looking at compiled or semantic representation.

This seems a bit inconsistent.  Suppose I round-trip from YANG to YIN
to YANG, and the result is different whitespace in the two YANG
modules.  The revision is the same, as explained above.  How is this
different from changing the whitespace in YANG directly?


> Thoughts?
> Joe
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