Metadata to encode lossy compression (by quantization) with @cofinoa

[czender]

See issue #403 for discussion of these changes.

Release checklist

• Authors updated in cf-conventions.adoc? Add in two places: on line 3 and under .Additional Authors in About the authors.
• Next version in cf-conventions.adoc up to date? Versioning inspired by SemVer.
• history.adoc up to date?
• Conformance document up to date?

For maintainers

After the merge remember to delete the source branch.
Tags are set at the conclusion of the annual meeting; until then, main always is a draft for the next version.

[czender]

Hi @davidhassell and @cofinoa . Please review this PR. I decided to omit the sections on optional keywords for pre- and post-metrics like relative precision. I would prefer to start small with the core of the proposal which is self-contained here. Other options can of course be added at your discretion now or later.

[czender]

@davidhassell and @JonathanGregory I have addressed and merged the comments from Jonathan's recent review. Please take another look and LMK what further changes are desired. (FYI I have also updated the reference implementation in NCO to adhere to this updated version).

[davidhassell]

Hi Charlie,

I really enjoyed reading this in detail. Hopefully all my comments are self explanatory, or are sufficiently explained.

They're either asciidoc formating; personal style suggestions (feel free to treat as you will); or - of more consequence - some suggestions in should/must, and clarifying (?) what's allowed. I'll be interested to hear what you think of the last category!

Cheers,
David

[czender]

@davidhassell Thank you for your careful review. You found many ways to make the new sections more clear and precise. I appreciate the time you spent. The review came with some outdated suggestions from April, which I finally just resolved without comment. Overall, I agree with ~90% of your suggested changes. However, as I mention in my first comment, I need guidance on whether to "Commit Suggestion" on those or merge them into my branch. Does "Commit Suggestion" actually commit the changes to my branch? I am worried that if I "Commit Suggestion" then the PR will have the changes and my branch will not and then I will be unable to create a new Convention document until the whole PR is actually merged. OK, those are just GitHub newbie issues.
The two areas that I need to hear back from you on are the ancillary_variables question I pose, and what to do with the Recommendation for the structure of the implementation attribute. Once we agree with what to do with those two issues, then all your suggestions will have been addressed.
Charlie

[davidhassell]

Hi Charlie,

Just to say that "commit changes" does indeed merge the change into your branch. I'll pick this up on Monday, if not before. Have a good weekend!

All suggestions either accepted as is, or revised after further discussion