# Globally unique identifiers

> Giving your Johnny.Decimal stuff globally-unique identifiers might be cool. I'm not sure why? But it feels cool.

The previous post regarding the [creative outputs pattern](/22.00.0145/) generated a bit of discussion on [Discord](https://discord.com/channels/822215537589354566/1428297259736371200), if you're interested.

That discussion led me to give the example of my most recent email to the mailing list, which just went out with the ID `D25.14.54+50068`.

Let's break that down.

- `D25` is our [system ID](/documentation/multiple-systems-overview) for the Johnny.Decimal business.
- `14.54` is the [small business](/sbs/) ID for 'electronic mailing lists'.
- `50068` is the ID in our [creative area](/15.02/) for this specific email.

Plausibly, someone else might have that exact same ID in _their_ system. Unlikely, but possible. So what if I wanted to reference that in a way that made it **globally unique**?

(More realistically, the ID `D25.14.54` might co-exist in the world, and the question of global uniqueness can be applied equally to it.)

## Prefix it

What if I had my own, guaranteed-globally-unique prefix? And you had yours, and anyone who wanted one had theirs.

Let's say that mine was `JDCMAL`, because we decide that they need to be 6 alphanumeric characters. Now I have:

`JDCMAL.D25.14.54+50068`

— and this short [DOI-like](https://en.wikipedia.org/wiki/Digital_object_identifier) identifier[^ras] now uniquely identifies this specific thing, globally.

[^ras]: 'Identifier' there creating a [RAS](https://en.wikipedia.org/wiki/RAS_syndrome).

To satisfy [some spec](https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml) I'd probably need to give it a URI scheme?

`JD://JDCMAL.D25.14.54+50068`

I'm not sure what I'd ever use it for. But it's an idea I keep coming back to.