This regexp is for the name component of the requests received by the registry and does not include the hostname or post. It's a path on the registry.

So I'm really no expert on the spec, so it's totally possible I'm wrong but, according to:

distribution/distribution@bbd41f4

optionalPort is a part of the remote-name component which in turn is used interchangeably with path according to the linked commit message. That made me think this could also be a part of a tag, is that wrong? It looks like it, according to your comment?

But before docker-py 7.0.0 it was possible to use ":" in a tag at least, see the linked bug report.

I'm not sure if this is or is not allowed by the spec, because I honestly find the wording in
the Pulling manifests paragraph quite confusing.

My main complaint would be the sentence:

Throughout this document, `<reference>` as a tag MUST be at most 128 characters in length and MUST match the following regular expression:

does this mean, that every tag must match this regex, or only a <reference> must match this regex when used as a tag? Can there be something else as a tag, that is not a reference? That's not 100% clear to me.

I think the following changes could it make more clear to the reader, but this is just my reading as a drive-by-contributor, so ymmv 🙂

• there is no dedicated paragraph for the correct syntax of things, it's thrown into an unrelated paragraph about pulling manifests (well there is a dedicated paragraph for this stuff, but it doesn't contain the needed information for tags, names, references etc.).
• clearly define what a tag is and is not, and what it's syntax it is supposed to match.
• it's not explained which kind of regex is used here, python-regex, golang regex, PCRE, etc.
• explanations that actually don't explain anything like name refers to the namespace of the repository but it seems to be not explained what a namespace nor a repository are in this context in this paragraph, it's also not explained in the paragraph about Definitions where I would expect those things to be defined (line 59 ff). Of course I have a rough understanding of the concept of namespacing and repositories in general, but their meaning can vary slightly depending on the context, so imho it would be nice to clarify that, if possible.

Maybe I just missed this information somewhere in the docs, or in some of the linked docs.

Sorry if this maybe got a little bit off topic.

Thanks for your work and help on this!

Distribution and distribution-spec are separate projects. There's a lot of overlap in the terms, but also inconsistent usage between the two. The concept of a reference from the distribution project doesn't exist in the distribution-spec. At least not yet.

The distribution-spec only deals with the http API, and the name field referenced here is within the Path of that request. It does not cover the Host field in the http API, that isn't specified in the spec.

Closing this one for now because we don't define a reference in OCI, yet.