SNS.yaml: HTTPS address of additional content?

I don’t understand the comment of the url field of the NnsProposal section in the SMS.yaml example file:

   # The HTTPS address of additional content required to evaluate the NNS
   # proposal.
   url: ~


  • “Additional content to evaluate the NNS proposal”

Should the proposer provide a link to some addition mathematic and source data used to calculate the initial parameters? Or it’s really about the text content of the proposal?

  • “HTTPS address”

I guess here it’s a “link to a website” or “URL” that is expected right?

  • No validation?

Assuming it’s an url, there is no validation? The other url in the yml file should match “Must be a string from 10 to 512 bytes.”, is that here also the case?

It simply maps to the URL field of the NNS proposal to create the SNS. Therefore all the rules of NNS proposal URLs apply.

It must be between 10 and 2048 bytes (not characters), the protocol must be HTTPS, and the domain must be The exact validation criteria are implemented here.

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Thanks for the explanation. I wanted to double-check the up-to-date SNS.yaml comment, given that I was referring to the old version. It seems that the new comment not only does not cover all the valuable information you shared but also seems incorrect.

# URL to the dapp controlled by the SNS project.
# Must be a string from 10 to 512 bytes.

If my finding is correct, maybe worth reviewing the comment in the sample file?

Haha, it is somewhat confusing but that is actually a different URL with different validation criteria. The SNS can have its own URL (e.g. to its homepage) that is separate from the URL attached to the proposal (which will generally be a forum post that explains some context for the proposal and possibly argues why the NNS governance participants should vote to approve it.

The validation criteria for the url field you quoted (the SNS’s url) is the same as the one for the NNS proposal URL, with the exception that its greatest allowed number of bytes is 512 and any domain is allowed.

This is worth explaining in the template though, so I will make a PR to do that later today. Thank you for your attention to this file, it is very welcome and the NNS team appreciates the chance to make it clearer.

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OOHHH then it was totally confusing to me to use an URL such as as example.

Thanks for the upcoming update of the example!

If I may Andre one more question about the (main) url if you do not mind.

The comment says:

# URL to the dapp controlled by the SNS project.

Is it correct that the URL of the SNS homepage must be controlled by the DAO?

I was under the impression that this was not mandatory. For example, the IC portal is not controlled by the NNS, but maybe that was a false assumption.

On the contrary, if this assumption is correct, should such a homepage be specified as url in the YAML file, or is another homepage expected in that case?

Maybe I should just wait for the updated documentation.

Thank you for pointing this out, I will make a PR to fix this

No, the URL can be anything and it is simply up to the NNS governance participants (followed by SNS governance participants) to decide what URL they want in this field. In fact not all SNSes even control a dapp. I will correct this in my PR as well

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